Right now, as the ground freezes, is the perfect time to protect your roses from vole damage during the coming winter. The correct approach is two-pronged: First, voles are deterred by castor oil applied to the ground in areas where they burrow, so applying castor oil, in the right dilution as winter sets in, should be your first line of defense. Next, the strategic placement of vole baits to kill those varmints that might make their way through your castor oil deterrent is your second line of defense.
Today (November 13th), I made my application of castor oil, which I buy inexpensively from Wal-Mart in their health and beauty area. It is also available from several vendors on line, if you do not have access to a Wal-Mart store. Please note that it is important to mix castor oil with liquid detergent as you dilute it with water in the proportions given below. The soap helps the oil dissolve in the cold water so that it doesn't stick to your sprinkling can. I inadvertently mixed some once, without the soap, and it gets very sticky and messy.
I discuss this two-pronged approach very thoroughly, plus much more, in my October 2012 blog post: "Voles". Here is the address of that blog:
http://theminnesotarosegardener.blogspot.com/2012/10/voles-and-roses.html
And here are a couple of excerpts from that blog post:
Castor Oil: This is the most effective solution I have found. Voles really don't like castor oil; apparently, from what I have read, it makes them sick, and they avoid an area on which it has been applied. Mix one or two teaspoons of castor oil (I use more rather than less) and one teaspoon of liquid detergent, per gallon of water, and apply it liberally around the bases of your roses and generally around your rose beds, where the voles might travel/burrow in the winter. The best time to do this is in late Fall, when the ground is lightly frozen, just before putting your final mulch or leaf cover around your roses. Around here, that would be in mid to late-November. I mix it in a 30-gallon trash container, pump it out with a sump pump, and apply it with a hose and watering wand, exactly like I do liquid fertilizers and potassium. You can also use a sprinkling can to apply it, if your garden isn't too big.
Note: Two teaspoons of castor oil per gallon in 30 gallons of water amounts to 10 ounces of castor oil. Wal-Mart's castor oil comes in 6 ounce bottles, so it takes a little more than 1 1/2 bottles for a 30 gallon trash can of the oil/soap/water mixture. A friend in Wisconsin reports that he is using one tablespoon (3 TSP) of castor oil and one tablespoon of soap per gallon and that's just fine. In this case, more is better to deter these little monsters. In fact, in 2017, I just used 2-bottles (12 oz.) of castor oil and 30 TBP of dish soap per 30 gallon can, just to keep it simple. This should give you some idea of how much to buy.
Pour the castor oil and soap into the 30 gallon can and then add water, stirring while you go. I also think it goes on just as easy with a sprinkling can as it does with a pump, so that's what I'm using now.
Rodent Baits: Killing voles is desirable, before they over-run you, but this is a touchy subject because rodent baits can also affect other animals, like neighborhood cats and dogs. The common rodent bait that you find in most stores is an anti-coagulant poison, which, when eaten a couple of times, stays in the intestines, causes massive internal bleeding and kills the animal. I used it in my rose beds for years, without thinking, until about five years ago when we got a new kitten and he managed to find a mouse or vole that had eaten it, in among the winter-protected roses. I will save you the terrible details, but it resulted in a very large emergency veterinary bill.... After that experience, I went to work researching what other non-coagulant rodent baits might be on the market, and I found one. The brand name is "Eraze", made by Motomco, the same company that makes the anti-coagulant baits. The active ingredient in this one is Zinc Phosphide, which is nonetheless a poison, but acts in a different way, killing small animals immediately after ingestion. There are conflicting opinions on this, but an article by Michigan State University indicates that it is less lethal to larger animals, such as cats and dogs, because their normal reaction after ingesting it would be to regurgitate it rather than digest it.
I have written a couple of other articles about vole protection, which contain several other comments and ideas. Here is my September 2013 post:
http://theminnesotarosegardener.blogspot.com/2013/09/voles-and-castor-oil.html
As always, please send your questions or comments to: jfalkersr@gmail.com .
Jack Falker
November 13, 2015
Friday, November 13, 2015
Wednesday, October 7, 2015
Winter-Protecting Your Roses
Here is an article I wrote for the October 2015 Twin Cities Rose Club Newsletter. While I reference Minnesota winter conditions, it is applicable anywhere in the upper-midwest and to virtually any kind of roses. The key message is to prevent your roses from repeatedly freezing and thawing. In a cold zone (3,4,5) that means keeping them frozen all winter.
Winter-Protecting Your Roses
Jack Falker
@mnrosegardener
Everyone in Minnesota knows they have to do something to
winter-protect their roses. However, not
everyone seems to know exactly what they’re supposed to accomplish and, thus,
what the best method might be. So let’s start with the one
basic principle that applies in all cold zones, i.e. USDA Zones 3, 4, 5 and
parts of 6, and to virtually all types of roses, whether they be hybrid teas or
shrubs; grafted or own-root.
Fact: The primary objective of winter protection in
the cold zones is to keep your roses frozen, not to keep them from freezing. There
seems to be a lot of confusion about this and, unbelievably, we still have
nurseries selling styrofoam rose cones, which serve as little ovens in the
winter, when the sun shines on them, causing plants to freeze and thaw
repeatedly, thereby killing them.
There are two basic ways of
keeping roses frozen where we live: (1) the Minnesota Tip and (2) mounding with
compost and insulating with leaves or hay.
Let’s be clear about the “tip” method:
When you tip your roses over in a trench, bury them in dirt and compost,
and put leaves on top, they are definitely going to freeze solid in the ground,
as the frost permeates down several inches. In fact, many Minnesota-tippers
soak their tipped roses, before turning off their water for the winter, so they
will be contained in blocks of ice. In
other words, the objective of the “tip” method is to freeze roses solid and
keep them frozen until spring
I personally believe that keeping
my roses standing upright and firmly planted, while mounding and insulating them,
is the best way to winter-protect. I tipped my roses for many years but always
felt that it was not horticulturally sound to partially uproot the plants and
cover them with dirt in mid to late October, when many of them were still in
bloom. The longer I did it, the more my gardening instincts (not to
mention my back) kept telling me I should be doing something
different. Take a look at my August 2012 Minnesota Rose Gardener blog
post "No Tipping Please”:
Many people, who have been tipping
their roses for years, feel trapped in the procedure because the bud unions of
their grafted hybrid teas are above the surface of the ground. This is a
basic problem, which is endemic to the tipping procedure. For a variety of sound horticultural reasons,
the bud unions of grafted roses and the crowns of own-root roses should not be
above ground, regardless of where you live, warm or cold. My advice to these
folks is: Instead of tipping your roses this year, dig them out entirely,
taking a good root ball, heel them into a trench, a foot or so deep, and cover
them with a good layer of dirt and mulch (to keep them frozen). Then in
the spring replant them in the same place, except this time plant them with the
bud unions several inches below the surface. If your garden is large, you
might do this in stages, some this year, some next year etc. Another
alternative might be to raise the level of soil in your beds so that your bud
unions are at least slightly below grade.
With your
roses properly planted, here is what I recommend for winter protection. First,
in mid-September and for six successive weeks, give your roses a potassium
feast to help their canes harden off, before the first hard freeze. It’s too late to start the feast this year
(I’m about to do my fourth application) but I believe potassium is important in
winter protection. For future reference,
here is the address of my most recent blog on the potassium feast:
Next,
gather any wood chips or other clean mulch in your beds and mound it around
your plants. Then, mound several shovels
of compost around every plant, so that the plant crowns are thoroughly covered.
My compost is primarily shredded oak leaves from last fall and hundreds
of pounds of composted Starbucks coffee grounds that I collect regularly. This
compost is full of worms and worm castings, so it's just what the roses need in
the spring, when I spread out the mounds and work the compost into the ground.
Next,
when it starts getting cold and your roses have stopped blooming, cut them down
to about 12 inches and bind them into tight bundles. One other thing you might
do, especially if you’ve had spider mites this summer, is to strip the leaves
off the plants and spray them with horticultural oil. (Don't worry, you're not
losing anything here; what you want is the strong new growth you’ll get in the
spring.)
The final
step is to prepare enough half-full plastic leaf bags to cover each of your
roses. (Don't use the new compostable bags; they break down over the
winter and leave you with piles of leaves to clean up!) Now, wait until
the ground freezes and, with the objective of keeping your roses frozen, slit
open the bottoms of your leaf bags and shove them down over each of your tightly
bundled plants, flush with the mounds.
So, can
you see how this approach will keep your roses frozen? When you start to
carefully roll the bags off your roses in the spring (to keep as many of the
leaves in the bags as possible for disposal or mulching), you will
find that many of the bags are still frozen to the mounds and that your roses
are encased in blocks of ice; exactly as you wanted them to be. In fact,
depending on how quickly it warms up, it may actually take longer for these
mounds to thaw than roses that have been tipped.
Regardless of how you choose to winter-protect your roses,
please keep firmly in mind that your objective in the cold zones is to keep them
frozen all winter. The other alternative, of course, would be to move to a warmer
zone, where your objective would be the opposite, i.e. to keep your roses from
freezing in the first place. No such
luck for me!
Jack Falker (@mnrosegardener)
10/01/2015
Friday, September 18, 2015
Time to Put Potassium on Your Roses
For those of us in the cold zones, i.e. USDA zones 3-6 (and maybe zone 7, given the vagaries of winter with recent polar vortex incursions), now is the time to begin feeding your roses a six week diet of potassium. Here is a quote from my posting on this subject in September 2013.
"In the six weeks before the first hard freeze (i.e., down to about 25 F. at night), give your roses a weekly "potassium feast" in each of those six weeks. Potassium blocks the growth-promoting effects of nitrogen and phosphorous, thereby hardening the canes in time for winter. I've been doing this for more than 20 years and I honestly can't remember the last time I lost a rose to winter weather here in Minnesota. Of course, I do other things to protect my roses from the Minnesota winter, as well. Here is my 2013 article on winter protecting your roses:
http://theminnesotarosegardener.blogspot.com/2013/09/winter-protecting-your-roses.html .
"In the six weeks before the first hard freeze (i.e., down to about 25 F. at night), give your roses a weekly "potassium feast" in each of those six weeks. Potassium blocks the growth-promoting effects of nitrogen and phosphorous, thereby hardening the canes in time for winter. I've been doing this for more than 20 years and I honestly can't remember the last time I lost a rose to winter weather here in Minnesota. Of course, I do other things to protect my roses from the Minnesota winter, as well. Here is my 2013 article on winter protecting your roses:
http://theminnesotarosegardener.blogspot.com/2013/09/winter-protecting-your-roses.html .
I learned this little trick in one of my first rose books: Burpee’s American Gardening Series, "Roses", by Suzanne Frutig Bales. Here's a quote from Suzanne's chapter on winter protection:
“Potassium is an important mineral for sturdy stems and foliage. Weekly feeds of a gallon of liquid potassium (1 tablespoon of muriate of potash (0-0-62), dissolved in 3 gallons of water) per bush, or a granulated feeding of potash magnesium (0-0-22), during the six weeks before the bushes go dormant, will give the bushes an additional boost for winter, extending their hardiness into another hardiness zone, perhaps two. Excess potassium, when available in greater amounts than nitrogen and phosphorus, is known as the ‘potassium feast’. It will block the growth-promoting effects of nitrogen and phosphorus, hardening the canes in time for winter.”
I did a little independent research on this, a couple of years ago, by talking to Dr. Peter Bierman, retired University of Minnesota Professor of Soil, Water and Climate. Peter told me that "... winter hardiness is one of the most important functions of potassium" and that the amounts recommended above..."would be a reasonable amount to apply for winter hardiness insurance and wouldn't be an excessive amount in terms of adding high salts." That squares with my 20 years-plus experience in administering the potassium feast to my roses each fall.
I did a little independent research on this, a couple of years ago, by talking to Dr. Peter Bierman, retired University of Minnesota Professor of Soil, Water and Climate. Peter told me that "... winter hardiness is one of the most important functions of potassium" and that the amounts recommended above..."would be a reasonable amount to apply for winter hardiness insurance and wouldn't be an excessive amount in terms of adding high salts." That squares with my 20 years-plus experience in administering the potassium feast to my roses each fall.
To clarify: The proportions are: 1 TBP muriate of potash per 3 gallons of water (or 1 TSP per gallon). So mixing in a 30 gallon trash container, you would use 10 TBP. Apply one gallon of this mixture on each rose every week. That’s not very much, but remember you’re repeating it six times. I also don't think the exact amount is critical and I usually err a bit on the side of a little more rather than less. (Please see my notes on using Potassium Sulfate below)
Several folks have asked me if they could "cheat" and do only three or four applications, using proportionally higher doses of potassium. My answer is always: "I don't know, but it's probably better than not doing it at all." However, my observations are that the roses harden off slowly, as the potassium applications continue over the six weeks and the weather gets colder. By the end of six weeks, the canes have turned a lovely shade of red and look ready for the winter ahead. With the canes thus hardened-off, they are less susceptible to the freeze-drying winter winds and naturally suffer less die back than if they their tissues were still soft. I don't know if the roses will harden off as well with fewer, larger applications of potassium, but I suspect not. However, don't let that discourage you if you get started late. A couple of applications will be better than nothing. Just try to get started earlier next year!
Another question is: where one can get potassium immediately to get started? The answer to that is farm stores that sell fertilizers to farmers, who use potassium (potash) as an agricultural fertilizer. Another source is suppliers to commercial growers and greenhouses. In the Twin Cities, the primary sources for me have been Waconia UFC Farm Supply and BFG Supply in St. Paul (formerly J.R. Johnson Supply). It's sold in 50 pound bags for about $.40/lb.
It was pointed out to me by a reader in England that a very good alternative to muriate of potash would be potassium sulfate (0-0-50), which is 50% potassium and 18% sulfur. This is interesting because adding sulfur to your roses in the fall has the effect of lowering the pH of your soil, which is desirable for most of us. A slightly acid pH around 6.0 (plus or minus) is best for roses. (See my posting "Mind your pH":
http://theminnesotarosegardener.blogspot.com/2013/06/mind-your-ph.html.)
Since potassium sulfate has a bit less potassium, i.e. 50%, compared with muriate of postash at 60%, you would use a little more potassium sulfate, perhaps 1.25 or 1.5 tsp per gallon. Again, I don't think the amount is super critical, so I would use 1.5 tsp/gallon to simplify things.
In any event, whatever form of potassium you use, I think this first step in the winterizing process is very important and I'm always amazed that many rosarians aren't aware of it. Mid to late September is the right time for most of us to get started, so find some potassium and begin your roses' feast very soon (I made my first application last week). I think you will be as pleasantly surprised by the results, as I have been over the years.
Here are two other articles on the potassium feast that I have previously published:
http://theminnesotarosegardener.blogspot.com/2012/08/potassium-special-k-ration-feast-for.html
http://theminnesotarosegardener.blogspot.com/2013/10/rose-potassium-feast-application-6.html
Jack Falker
@mnrosegardener
jfalkersr@gmail.com
Several folks have asked me if they could "cheat" and do only three or four applications, using proportionally higher doses of potassium. My answer is always: "I don't know, but it's probably better than not doing it at all." However, my observations are that the roses harden off slowly, as the potassium applications continue over the six weeks and the weather gets colder. By the end of six weeks, the canes have turned a lovely shade of red and look ready for the winter ahead. With the canes thus hardened-off, they are less susceptible to the freeze-drying winter winds and naturally suffer less die back than if they their tissues were still soft. I don't know if the roses will harden off as well with fewer, larger applications of potassium, but I suspect not. However, don't let that discourage you if you get started late. A couple of applications will be better than nothing. Just try to get started earlier next year!
Another question is: where one can get potassium immediately to get started? The answer to that is farm stores that sell fertilizers to farmers, who use potassium (potash) as an agricultural fertilizer. Another source is suppliers to commercial growers and greenhouses. In the Twin Cities, the primary sources for me have been Waconia UFC Farm Supply and BFG Supply in St. Paul (formerly J.R. Johnson Supply). It's sold in 50 pound bags for about $.40/lb.
It was pointed out to me by a reader in England that a very good alternative to muriate of potash would be potassium sulfate (0-0-50), which is 50% potassium and 18% sulfur. This is interesting because adding sulfur to your roses in the fall has the effect of lowering the pH of your soil, which is desirable for most of us. A slightly acid pH around 6.0 (plus or minus) is best for roses. (See my posting "Mind your pH":
http://theminnesotarosegardener.blogspot.com/2013/06/mind-your-ph.html.)
Since potassium sulfate has a bit less potassium, i.e. 50%, compared with muriate of postash at 60%, you would use a little more potassium sulfate, perhaps 1.25 or 1.5 tsp per gallon. Again, I don't think the amount is super critical, so I would use 1.5 tsp/gallon to simplify things.
In any event, whatever form of potassium you use, I think this first step in the winterizing process is very important and I'm always amazed that many rosarians aren't aware of it. Mid to late September is the right time for most of us to get started, so find some potassium and begin your roses' feast very soon (I made my first application last week). I think you will be as pleasantly surprised by the results, as I have been over the years.
Here are two other articles on the potassium feast that I have previously published:
http://theminnesotarosegardener.blogspot.com/2012/08/potassium-special-k-ration-feast-for.html
http://theminnesotarosegardener.blogspot.com/2013/10/rose-potassium-feast-application-6.html
Jack Falker
@mnrosegardener
jfalkersr@gmail.com
Thursday, September 17, 2015
How Winter Affects Roses (Revisited)
This is the time of year when everyone in the cold zones should start thinking about winter-protecting their roses. The sooner you get going, the easier the task will be in a couple of months. I think this blog post, written in the winter of 2013/14, is worth revisiting for those of my readers who may have missed it. I would particularly call your attention to my articles referenced herein about the annual postassium feast, which should begin in mid-September, in time to "harden off" your roses for winter.
At the peak of winter here in the cold zones, our roses are "winter-protected" to help them survive the sub-zero temperatures of USDA zones 4, 5, and 6. Most folks look out at their roses covered (hopefully) with a nice layer of snow and believe their roses are dormant; just waiting to thaw out, break dormancy and start growing again. But wait.... Did you know that only species roses, such as Rosa Rugosa, Rosa Glauca, Rosa Gallica etc. go through a dormancy cycle and that all modern, repeat-blooming, "remontant" roses do not? So what's going on here with modern roses in winter?
Before I try to answer that question, I want to say that I recently learned much of this from "Dormancy in Roses", an excellent four-part series in the American Rose, during 2013 and early 2014, by Dr. Gary Ritchie of Olympia, Washington (see footnote below). I will quote Gary several times in this post and want to give him full credit for his research and opinions. However, I also want to note that Gary's articles have raised some important issues for me, based on my many years of successfully growing modern roses in Minnesota; in particular, why keeping modern roses frozen hard in the winter is what keeps them alive, rather than killing them outright. This seems somewhat contrary to the conclusion of Part 4 of Gary's article, where he says:
"I've not seen data on specific cold hardiness of modern roses but experience indicates that it is modest at best. So, while we enjoy continuous bloom throughout the summer, we face the annual chore of winter protecting our roses. Here in the moderate coastal Northwest, this requires no more than mounding up our plants in fall. But in more extreme climates winter protection can be much more difficult and problematic -- sometimes even requiring burying the plants underground to assure their over-winter survival."
http://theminnesotarosegardener.blogspot.com/2013/09/winter-protecting-your-roses.html
Here is how two of my rose beds looked on Christmas Day 2013:
Now, just in case I have given the impression that I'm not growing hybrid teas in Minnesota winters, here is my winter-protected Elina on a -2 F. afternoon in Edina. The reason the leaf bag is showing under the snow is that we had a record-breaking 48 F. the day before I took this picture; a 50 degree swing! And that's what winter protection is all about in zone 4/5: to keep the roses from thawing and re-freezing in these crazy temperature swings!
.JPG)
Dr. Gary Ritchie's point about modern roses not going into dormancy is obviously correct. Unlike woody perennials like Rhododendron or lilacs, roses apparently do not have a dormancy "chilling requirement" in order to generate next season's bloom cycle. Rather, as Gary says, modern roses, as remontant, repeat-blooming plants, "by their very nature, fail to go dormant in winter. So they have a much-reduced ability to cold harden." In other words, rose canes die back in winter because they do not sufficiently "cold harden" and this die-back can only be controlled at the crown or bud union levels by proper winter-protection, as described above. This affirms something that I have advocated for many years, i.e., repeated applications of potassium in the fall to "cold-harden" rose canes before the first hard freeze. My experience, over more than 20 years, is that hardening rose canes off with a potassium feast has the effect of significantly reducing cane die back in the winter. Please see my several articles about the "potassium feast":
http://theminnesotarosegardener.blogspot.com/2014/09/potassium-feast-for-your-roses.html
http://theminnesotarosegardener.blogspot.com/2012/08/potassium-special-k-ration-feast-for.html
But something else seems to be happening here
What he is saying is that dormant plants apparently have an internal clock mechanism buried deep in their DNA that tells them it's time to start growing again, after they have been exposed to a certain number of hours or days of cold weather. However, what happens if that internal clock tells them it's time to grow and they're still frozen solid?
I had been thinking about this since last spring and Gary Ritchie's four-part series in the American Rose was such an “a-ha” moment for me, that I couldn't wait for the next installment to come. Gary might not agree, but it seems logical to me that, while modern (non-species) roses do not experience dormancy, per se, they might share some form of the so called "chilling requirement" of species roses. There is much we don't know about the effects of winter on roses but, by observing the effects of the weather anomalies we are currently experiencing, we can learn a lot about what makes our roses tick and how we can better protect them in winter. Unfortunately, we can't do much about the undue length of some winters, except to realize that not all winter effects on roses are related to extreme low temperatures.
I would be very interested in the reactions of readers to the theories I have set forth in this article. My findings are 100% empirical and can be enhanced by the observations of others growing roses in cold zones. As always, please let me know what you think.
Jack Falker
jfalkersr@gmail.com
September 17, 2015
Note: Dr. Gary Ritchie's four articles on Dormancy appeared in the May/June, July/August, and September/October, 2013, and the January/February 2014 issues of the American Rose. By the way, articles like these, written by outstanding rose-scientists like Gary Ritchie, are one more reason that all rosarians should be members of the American Rose Society!
At the peak of winter here in the cold zones, our roses are "winter-protected" to help them survive the sub-zero temperatures of USDA zones 4, 5, and 6. Most folks look out at their roses covered (hopefully) with a nice layer of snow and believe their roses are dormant; just waiting to thaw out, break dormancy and start growing again. But wait.... Did you know that only species roses, such as Rosa Rugosa, Rosa Glauca, Rosa Gallica etc. go through a dormancy cycle and that all modern, repeat-blooming, "remontant" roses do not? So what's going on here with modern roses in winter?
Before I try to answer that question, I want to say that I recently learned much of this from "Dormancy in Roses", an excellent four-part series in the American Rose, during 2013 and early 2014, by Dr. Gary Ritchie of Olympia, Washington (see footnote below). I will quote Gary several times in this post and want to give him full credit for his research and opinions. However, I also want to note that Gary's articles have raised some important issues for me, based on my many years of successfully growing modern roses in Minnesota; in particular, why keeping modern roses frozen hard in the winter is what keeps them alive, rather than killing them outright. This seems somewhat contrary to the conclusion of Part 4 of Gary's article, where he says:
"I've not seen data on specific cold hardiness of modern roses but experience indicates that it is modest at best. So, while we enjoy continuous bloom throughout the summer, we face the annual chore of winter protecting our roses. Here in the moderate coastal Northwest, this requires no more than mounding up our plants in fall. But in more extreme climates winter protection can be much more difficult and problematic -- sometimes even requiring burying the plants underground to assure their over-winter survival."
Here is how I would re-phrase Gary’s quote (above) from my perspective in zone 4/5:
"I've not seen data on specific cold hardiness of modern roses, but experience indicates that, with good winter protection, most modern roses, including budded hybrid-teas, are very cold-hardy, as long as they are allowed to freeze solid and stay frozen all winter. Here in Minnesota (zones 3, 4, and 5), winter protection begins with planting bud unions four to six inches deep, mounding with dirt or compost in the fall, and subsequently winter-protecting with leaves or hay after the ground freezes in late fall or early winter. Another alternative is the Minnesota Tip method of burying plants underground. Both methods have as their objective keeping roses frozen throughout the winter; not to keep them from freezing, which is virtually impossible in our zone 4/5 winters." (JRF Quote)
In other words, the whole purpose of winter-protecting roses in the cold zones, where the ground freezes from several inches to more than a foot down, is to keep roses from repeatedly freezing and thawing. The only exception to this might be the use of insulated R7.5 construction blankets, which are gaining popularity in Minnesota. My friend and TCRC mainstay, Deb Keiser, who manages the Virginia Clemens Rose Garden in St. Cloud, believes that putting construction blankets down before the ground freezes keeps her roses from freezing in the first place (which is quite an achievement in St. Cloud!). But the principle is the same, whether the ground freezes under the blankets or not: i.e., to keep your roses from repeatedly freezing and thawing. This can be problematic here in the Twin Cities (now in zone 5) and even more so in zones 6 and 7, where mid-winter thaws are more frequent. Take a look at my recent article on winter protection:
http://theminnesotarosegardener.blogspot.com/2013/09/winter-protecting-your-roses.html
Here is how two of my rose beds looked on Christmas Day 2013:
Buck Earth Songs under a foot of snow insulation
Terraced Canadians and Bucks
Now, just in case I have given the impression that I'm not growing hybrid teas in Minnesota winters, here is my winter-protected Elina on a -2 F. afternoon in Edina. The reason the leaf bag is showing under the snow is that we had a record-breaking 48 F. the day before I took this picture; a 50 degree swing! And that's what winter protection is all about in zone 4/5: to keep the roses from thawing and re-freezing in these crazy temperature swings!
.JPG)
Above: Elina in a Minnesota Winter
Dr. Gary Ritchie's point about modern roses not going into dormancy is obviously correct. Unlike woody perennials like Rhododendron or lilacs, roses apparently do not have a dormancy "chilling requirement" in order to generate next season's bloom cycle. Rather, as Gary says, modern roses, as remontant, repeat-blooming plants, "by their very nature, fail to go dormant in winter. So they have a much-reduced ability to cold harden." In other words, rose canes die back in winter because they do not sufficiently "cold harden" and this die-back can only be controlled at the crown or bud union levels by proper winter-protection, as described above. This affirms something that I have advocated for many years, i.e., repeated applications of potassium in the fall to "cold-harden" rose canes before the first hard freeze. My experience, over more than 20 years, is that hardening rose canes off with a potassium feast has the effect of significantly reducing cane die back in the winter. Please see my several articles about the "potassium feast":
http://theminnesotarosegardener.blogspot.com/2014/09/potassium-feast-for-your-roses.html
http://theminnesotarosegardener.blogspot.com/2012/08/potassium-special-k-ration-feast-for.html
But something else seems to be happening here
Over the last several years, as the Twin Cities metro has moved solidly into zone 5, my observations indicate that modern roses may exhibit a characteristic, which may be related to the chilling requirement inherent in plants that experience dormancy in winter.
Even though our winters are warmer, in terms of extreme minimum temperatures (EMT), they seem to be just as long, or perhaps even longer in certain years, thereby keeping our roses frozen for a longer period of time. For example, our ground (and therefore our roses) stayed frozen into late April or early May in 2013, and we had snow on the ground into early May. This is 2-4 weeks later than normal. What happened in May, once the ground thawed out, was that the roses had a very hard time getting started and there seemed to be more die-back than usual, even with shrubs that are zone 3 and 4 hardy. One of our husband-wife TCRC members,who have had good success over the years planting their hybrid tea and shrub roses with bud-unions and root crowns six inches below ground level, and using minimal winter protection above ground, lost a number of roses in 2013, even though the same method had worked perfectly in colder EMT winters.
In other words, with a 2013 EMT of -13 (well above the median for zone 5), our roses actually seemed like they had been through a much harder winter. So it would appear that the length of time roses are frozen, not just the low temperature in a given year, impacts survivability. After all, if you think about it, frozen is frozen; the only thing that happens with a lower temperature is that the ground freezes deeper and the roses take longer to thaw out and start growing in the new season. But what happens to them when the winter is so long that they can't start growing again in a timely way? To my knowledge there is no scientific reasoning for this phenomenon. However, I found a clue in Part III of Gary Ritchie's series, where he speaks of cold weather breaking dormancy in plants. Speaking of dormant plants in the first person, he says:
"...One way would be somehow to keep track of the amount of cold weather to which you had been exposed during winter. After a certain number of hours or days of cold exposure had occurred you would have a clear indication that winter was finally over and it was safe to resume growth. This is exactly what plants do...."
What he is saying is that dormant plants apparently have an internal clock mechanism buried deep in their DNA that tells them it's time to start growing again, after they have been exposed to a certain number of hours or days of cold weather. However, what happens if that internal clock tells them it's time to grow and they're still frozen solid?
Now, this is pure conjecture on my part but, based on my observations in the past year, I would theorize that (1) modern roses, although they do not experience dormancy, might share a similar DNA clock mechanism with plants that do, such as their first-cousins, the species roses; and (2) the growth signal coming from within the plant might be distorted by longer than historically normal periods of remaining frozen, such that the plant's internal growth pattern is interrupted, or even curtailed altogether, thereby causing much slower growth or even plant death. This could account for what I and a number of Minnesota friends experienced in our warmer, but longer than normal, winter of 2013. This was truly something I had never seen in my near-lifetime of growing roses in zones 4, 5 and 6.
I would be very interested in the reactions of readers to the theories I have set forth in this article. My findings are 100% empirical and can be enhanced by the observations of others growing roses in cold zones. As always, please let me know what you think.
Jack Falker
jfalkersr@gmail.com
September 17, 2015
Note: Dr. Gary Ritchie's four articles on Dormancy appeared in the May/June, July/August, and September/October, 2013, and the January/February 2014 issues of the American Rose. By the way, articles like these, written by outstanding rose-scientists like Gary Ritchie, are one more reason that all rosarians should be members of the American Rose Society!
Sunday, July 12, 2015
The Beetles Are Coming! The Beetles Are Coming! 2015 Edition
Note: This is a revised version of my previous JB posts from May 2012 and January 2013. In particular, it changes my conclusions on pesticides, particularly imidacloprid, which has recently been implicated in bee colony collapse disorder, and the pyrethroid Demand CS (Lambda Cyhalothrin).
Japanese Beetles are the scourge of Twin Cities rose gardens, as well as virtually everywhere south of Minnesota. From my perch in Edina, Minnesota they are, without a doubt, my biggest problem as a rose grower. The reason is that there are so many of them – thousands and thousands -- and there is so little I can do about stopping them. There is nothing more frustrating than admiring a perfect new rose bud and finding a couple of ugly Japanese Beetles (JBs) burrowing deeply inside the bud, eating it from the inside out… sickening.
I hate these bugs! Here's how they looked in two of my beds this afternoon. Normally I would have been on JB patrol in my gardens sooner but I was busy with other things and this was the result by late afternoon:
And here's how they looked after they joined their predecessors of today, in my can of soapy water, which I carry wherever I go on JB patrol in the garden during July and August. This is kind of time consuming, but absolutely the right way to deal with JBs, at least in a home or small public garden. Much more on that later.
It's interesting that there seems to be a north/south line of demarcation in the Twin Cities for JBs. We live in the southwestern part of the metro area and have been seeing JBs for just the last six or seven years, peaking in 2012, as our winters have become less severe, statistically moving us into the range of USDA zone 5. Most gardeners in the northern suburbs, roughly 10 miles from us, as well as gardeners in St. Cloud, northwest of us, have never seen JBs. That would indicate that JBs are harbingers of climate change, as are many other insect species. Since 2012, we have had lighter infestations, until this year, which is quite heavy, approaching the levels of 2012, at least here in Edina.
To understand what we can and can't do about these garden monsters, let’s first understand how JBs function. JBs emerge in June from grubs in lawn turf, the eggs of which were laid in the lawn the previous summer by JB adults. Here is a very good diagram, prepared by the University of Minnesota, showing what happens:
By the way, the U of M article I’m quoting is definitely the best I’ve seen on JBs (Go Gophers) and is available at this address: http://www1.extension.umn.edu/garden/insects/find/japanese-beetles/
Until recently, the only insecticides that were even mildly effective on JBs (i.e. imidacloprid and carbaryl) were also very hard on the environment, particularly on bees and other beneficials. Also, they just killed the JBs that landed in the first couple of days, while swarms of these monsters just kept on coming.
There is only one completely safe solution to JB control in the rose garden: i.e., pick them off and drown the buggers. A beneficial side-effect of that method is that it requires you to be in the rose garden at least twice a day and results in a more thorough job of deadheading and assessing other issues, not to mention enjoying the beauty of your roses. For large public gardens and commercial nursery farming operations, Lambda Cyhalothrin (Demand CS) works better than other insecticides I have tried and appears to be the lesser of evils in damaging beneficials, despite the fact that it wipes out all beneficial beetles.
Jack Falker
August 5, 2015
Japanese Beetles are the scourge of Twin Cities rose gardens, as well as virtually everywhere south of Minnesota. From my perch in Edina, Minnesota they are, without a doubt, my biggest problem as a rose grower. The reason is that there are so many of them – thousands and thousands -- and there is so little I can do about stopping them. There is nothing more frustrating than admiring a perfect new rose bud and finding a couple of ugly Japanese Beetles (JBs) burrowing deeply inside the bud, eating it from the inside out… sickening.
I hate these bugs! Here's how they looked in two of my beds this afternoon. Normally I would have been on JB patrol in my gardens sooner but I was busy with other things and this was the result by late afternoon:
And here's how they looked after they joined their predecessors of today, in my can of soapy water, which I carry wherever I go on JB patrol in the garden during July and August. This is kind of time consuming, but absolutely the right way to deal with JBs, at least in a home or small public garden. Much more on that later.
It's interesting that there seems to be a north/south line of demarcation in the Twin Cities for JBs. We live in the southwestern part of the metro area and have been seeing JBs for just the last six or seven years, peaking in 2012, as our winters have become less severe, statistically moving us into the range of USDA zone 5. Most gardeners in the northern suburbs, roughly 10 miles from us, as well as gardeners in St. Cloud, northwest of us, have never seen JBs. That would indicate that JBs are harbingers of climate change, as are many other insect species. Since 2012, we have had lighter infestations, until this year, which is quite heavy, approaching the levels of 2012, at least here in Edina.
To understand what we can and can't do about these garden monsters, let’s first understand how JBs function. JBs emerge in June from grubs in lawn turf, the eggs of which were laid in the lawn the previous summer by JB adults. Here is a very good diagram, prepared by the University of Minnesota, showing what happens:
Life cycle of Japanese beetle: egg, grub, and adult stages. In June, the grub turns into a pupa. It emerges from the soil in late June and July as an adult, to mate and lay eggs. Females live for a few weeks feeding on trees, shrubs and roses in the morning, returning to the turf in the afternoon to lay more eggs. Eggs hatch in July and grubs are almost full grown by late August. Grubs dig deep in the soil for the winter months and then move upward in spring as the soil warms. Grubs do best in warm, slightly moist soil that has plenty of organic matter and tender grasses. However, they can survive in almost any soil.
Note that the grubs are coming to the surface in April and May and are feeding on the roots of your lawn as we speak. So there is something you can do about the grubs in your lawn right now. If you turn over a couple of square feet of turf around your rose garden and find one inch long white grubs, you can apply a grub control product, such as “Grubex” or “Menard’s Grub Control” to your lawn right now and probably kill them off. I have been doing this (and other things like Milky Spore and nematode treatments) for the last seven or eight years and I can simply say that I have wasted my time and money. Why? Well, I’m sure I killed off the JB grubs in my lawn, but what about the thousands and thousands of grubs in my neighbors’ lawns and in the turf of several golf courses in my vicinity. The U of M says that JBs fly thousands of feet from where they emerge (think roughly a mile here) and they are looking for their favorite food… read ROSES! So it might make me feel good to think I killed off the JB grubs in my lawn, but I am completely helpless when it comes to killing off the grubs in neighboring lawns and golf courses a mile away. I don’t mean to say that you shouldn’t try to kill the grubs in your lawn (especially, the “U” says, in August and September each year), but that is probably more important in preserving the quality of your lawn than keeping JBs from eating your roses.
As mentioned above, Milky Spore has not proven effective, probably for the same reasons, i.e. it might work on the grubs in my lawn but the majority of invading JBs come from a five mile radius around me, not from my property. Here's what the University of Minnesota JB article says about it:
Milky spore disease – is caused by the bacteria Bacillus popilliae and is sold under the names of Japidemic Doom and Milky Spore. Recent trials with these formulations have not reduced Japanese beetle grub numbers in turf.
As mentioned above, Milky Spore has not proven effective, probably for the same reasons, i.e. it might work on the grubs in my lawn but the majority of invading JBs come from a five mile radius around me, not from my property. Here's what the University of Minnesota JB article says about it:
Milky spore disease – is caused by the bacteria Bacillus popilliae and is sold under the names of Japidemic Doom and Milky Spore. Recent trials with these formulations have not reduced Japanese beetle grub numbers in turf.
That said; let’s take a look at how to try to control adult JBs on your roses. Note I said “try” because there is really no completely satisfactory solution. So, here’s the most important point of this article: The best way to control JBs is with your fingers and soapy water! Don’t be fooled by the easy solutions presented by insecticides; just like killing the grubs in your lawn, the JB adults you kill with insecticides are just the tip of the iceberg that is flowing up and down your street into your garden. The only sure-fire way to deal with JBs is to pick or shake them off your roses into a can of soapy water. JBs are really quite vulnerable to this method because their primary defense mechanism is to simply drop off the plant they are destroying, down to the dirt or grass. They don’t sting or bite and they move pretty slowly, especially early in the morning and at dusk, so the “trick” here is to hold your can under the target JBs and pick or shake them off the plant into the soapy-water. I’m as squeamish as the next person about picking bugs with my fingers, so I wear nitrile surgical or milking gloves (that I get in the dairy-farm department at Fleet Farm) and I use a plastic 2 lb. coffee can, which has a built-in handle and a big opening. I squirt a little dishwashing soap in the can and fill it about half-full with water. The soap breaks the surface tension of the water and they are very helpless once they hit it. While this process is laborious, especially because it goes on for two months, through thousands of JBs, there is some pleasure in watching the little demons meet their end, knowing that every JB you drown will never fertilize or lay an egg for next year’s hatch. Each night, I dispose of the dead JBs either by flushing them down a toilet or putting them in my yard-waste bin (covered). Note that they become very smelly if you leave them in the soap-water overnight.
This is important! Don’t be tempted to squish JBs and throw them on the ground after you pick them off your roses (even though it would give you (and me) so much pleasure to do so). When you squish a female JB her sexual-attractant pheromone is spewed out and brings in every male in the neighborhood!
Likewise, don’t buy JB traps. They use that same sexual pheromone to bring JBs to the traps, and many more JBs come into your yard than ever find their way into the traps. If you are just compelled to buy traps, buy them for your neighbors and keep them out of your own yard! Oh, and be sure to empty your neighbors’ traps every day, because all those dead JB females just keep attracting more suitors, which are bound to find your roses. Here’s what the “U” has to say about JB traps:
"JB traps: are they useful in controlling JB adults?"
“Pheromone traps contain a lure with the scent of geraniums and rose (geraniol) and the sex pheromone of the JB female. The pheromone is very powerful and will call in beetles from a few thousand feet. Research demonstrated that more beetles fly toward traps than are caught, resulting in surplus beetles that feed on your plants. Think twice before purchasing and installing a pheromone trap.” (Emphasis mine.)
Insecticide Control of JB Adults
Note: After several years of experimenting with insecticide control of JBs, I am firmly convinced that it is the wrong approach in the home or small public garden for the simple reason that it massacres all other beetles in the garden, most notably the lady beetle, which is perhaps the most important beneficial bug for controlling a variety of insect garden pests. Also, all of these insecticides harm pollinators, especially bees, as well as virtually all other beneficials such as wasps, syrphid flies, lacewings, minute pirate bugs etc., as well as predatory mites, which attack a large variety of pests such as aphids, thrips and two-spotted spider mites. Once I began controlling JBs with insecticides, many of my bees disappeared and I experienced an infestation of all the pests listed above; a lesson well learned! It has taken me two years to re-establish beneficial bugs in my gardens and I will never again spray insecticides to control JBs.
Having said that, there comes a time in very large public gardens and the gardens of commercial growers when JB infestation occurs and it’s just too hard and time consuming to hand pick them. I vividly remember a visit in 2007 to the lovely Elizabeth Park Rose Garden in Hartford, CT, in which the JB infestation was absolutely shocking, and nothing was being done to stop it. The garden was literally in ruins, which was unacceptable. That same situation occurs with commercial rose growers who cannot let their crops be ruined. At some point, these large gardens and nursery farms must revert to insecticide control, unfortunately at the expense of killing off beneficial insects; i.e., the lesser of two evils. Note: After several years of experimenting with insecticide control of JBs, I am firmly convinced that it is the wrong approach in the home or small public garden for the simple reason that it massacres all other beetles in the garden, most notably the lady beetle, which is perhaps the most important beneficial bug for controlling a variety of insect garden pests. Also, all of these insecticides harm pollinators, especially bees, as well as virtually all other beneficials such as wasps, syrphid flies, lacewings, minute pirate bugs etc., as well as predatory mites, which attack a large variety of pests such as aphids, thrips and two-spotted spider mites. Once I began controlling JBs with insecticides, many of my bees disappeared and I experienced an infestation of all the pests listed above; a lesson well learned! It has taken me two years to re-establish beneficial bugs in my gardens and I will never again spray insecticides to control JBs.
Until recently, the only insecticides that were even mildly effective on JBs (i.e. imidacloprid and carbaryl) were also very hard on the environment, particularly on bees and other beneficials. Also, they just killed the JBs that landed in the first couple of days, while swarms of these monsters just kept on coming.
In 2011, it was brought to my attention by a commercial pesticide applicator that one of the pyrethroids, Lambda Cyhalothrin, sold as Demand CS, might be effective in controlling JBs. I tested it in the summer of 2012 and was very surprised and pleased at how effective it was. When I used it the first time, I had an infestation of hundreds of beetles in my beds. Immediately upon spraying, the beetles literally went away and did not come back for upwards of five days, at which time their numbers were few enough that I could resume picking and drowning them. After about a week, I sprayed again and the process repeated itself. I continued to do this for the rest of the summer until the JBs were finished hatching.
Demand CS utilizes a unique capsule suspension of the Lambda-Cyhalothrin which keeps it active on the roses for upwards of a week. This apparently acts as a repellant to JBs, since they will not land on the plants when the insecticide is present. The University of Minnesota website on JBs mentions the Pyrethroids (and Lambda Cyhalothrin specifically) as effective control insecticides for JBs. Here's that URL again:
http://www1.extension.umn.edu/garden/insects/find/japanese-beetles/ .
Note, in particular, that the "U" does not mention toxicity to bees with Lambda Cyhalothrin, whereas most other pyrethroids are shown to be toxic to bees and other beneficial insects. However, I noted, subsequent to my trials in 2012, that there was, indeed, an effect on beneficial insects in my gardens, especially on lady beetles and, to a lesser extent, bees. In particular, I experienced the worst infestation of aphids I have ever seen, causing us to take other insecticide steps. In a large public or commercial garden that may be the lesser of two evils and a price worth paying to control the JBs. In any event, our experience would indicate that Lambda Cyhalothrin is the best all-around insecticide alternative for JB control.
Note, in particular, that the "U" does not mention toxicity to bees with Lambda Cyhalothrin, whereas most other pyrethroids are shown to be toxic to bees and other beneficial insects. However, I noted, subsequent to my trials in 2012, that there was, indeed, an effect on beneficial insects in my gardens, especially on lady beetles and, to a lesser extent, bees. In particular, I experienced the worst infestation of aphids I have ever seen, causing us to take other insecticide steps. In a large public or commercial garden that may be the lesser of two evils and a price worth paying to control the JBs. In any event, our experience would indicate that Lambda Cyhalothrin is the best all-around insecticide alternative for JB control.
Imidacloprid (Merit) is still useful in JB control as a way of killing JB grubs in the turf and as a systemic in trees, particularly against emerald ash borer. It can also be used as a systemic in roses, applied as a soil drench in May, but note that it is only effective if the JBs land on the stems and leaves of the plants. In other words, it is not effective in the blooms, which is where most JBs (and bees) land.
Please note that imidacloprid (Merit) has been shown to be toxic to bees and is suspected as a leading factor in bee colony collapse disorder. For that reason it has been banned in Europe and parts of Canada and there is a move afoot to ban it in the U.S. In my opinion, therefore, it should be used only as a turf grub control, if at all. One caution: If you use Imidacloprid on your lawn to kill JB grubs, do not apply it around any edible fruit trees you might have, since it is absorbed by the fruit and you will end up eating it; not a good idea.
ConclusionThere is only one completely safe solution to JB control in the rose garden: i.e., pick them off and drown the buggers. A beneficial side-effect of that method is that it requires you to be in the rose garden at least twice a day and results in a more thorough job of deadheading and assessing other issues, not to mention enjoying the beauty of your roses. For large public gardens and commercial nursery farming operations, Lambda Cyhalothrin (Demand CS) works better than other insecticides I have tried and appears to be the lesser of evils in damaging beneficials, despite the fact that it wipes out all beneficial beetles.
By all means, also read the University of Minnesota piece, at the URL address cited earlier in the article. You can also find it by doing a Google search for: Japanese Beetles, Minnesota.
If you have questions or ideas, please let me know. at: jfalkersr@gmail.com or 612 385-6226.Jack Falker
August 5, 2015
Wednesday, April 1, 2015
Uncovering Your Roses and When to Prune
When to uncover your roses in the Spring is really quite easy to determine if you remember the reason for covering them in the first place. That is, to keep them from freezing and thawing repeatedly over the winter months, which is what kills them. In the Upper Midwest, where I live, we finish covering our roses at the point when the ground freezes and it is our objective to keep them frozen all winter. Let me repeat that: In the Upper Midwest, we don't cover our roses to stop them from freezing; we cover them to keep them frozen. Every method of winter protection in this climate, including the Minnesota Tip, has that same objective, and I am always surprised when people don't understand that. Our ground freezes generally at least two feet down and sometimes, as in the winter of 2013-14, it freezes down as much as four feet. So it shouldn't be hard to understand that everything planted at the surface freezes, regardless of how you insulate.
For folks in warmer areas, like the warmer parts of zone 6 and throughout zone 7, where the ground freezes down a few inches and then repeatedly thaws and refreezes throughout the winter, the purpose of winter cover would be the same, i.e. to keep the roses from repeatedly freezing and thawing, but in this case it would be to insulate them to prevent them from freezing in the first place. It really amounts to the same thing, however.
Given these principles, when to uncover your roses should be obvious, wherever you live. It is simply when the danger of freezing and thawing has passed. Around here, that usually occurs sometime in the first two weeks of April but virtually never in March, regardless how warm it might get for a few days. Let me give you a recent example. In the spring of 2012 we had 70 and 80 degree weather in mid-March causing fruit trees to blossom etc., but in the next week we had 10 degree weather followed by at least two weeks of below freezing weather. This caused the loss of almost the entire apple crop in Minnesota and Wisconsin and virtually the entire cherry crop in western Michigan. If you had uncovered your roses in March 2012, thereby allowing them to thaw out, you would have suffered severe damage when they froze again.
I realize that it is very tempting to uncover your roses when it first warms up in the spring. If you use the leaf bag method, which I have advocated in my blogs, you can choose to partially uncover your roses by rolling the leaf bags back but leaving them ready to replace, if the weather turns cold again. This approach allows the plants to begin thawing and to soak up spring rains, while keeping your options open for easy recovering. I would say that I use some form of this approach almost every year, especially when it starts to rain (vs snow!).
Today, April 1st, it was 82 degrees and we are expecting thunderstorms tonight so I decided to go out and roll the bags off my roses, while keeping them close-by, if I have to roll them back
Wherever you live, my suggestion is to watch the seven-day weather forecasts in early April and try to determine when your nights stay consistently above 25 F (-4 C). If you keep the mounds around your plants, even if you pull the bags back, temps down to 25 F will not refreeze your plants. If you are in doubt, just keep your plants covered until mid-April, around here. It won't hurt them.
And here's a quote from Paul Douglas' weather blog today:
"Another Relapse After a May-like temperature swoon today temperatures cool off later this week, a taste of early March shaping up for early next week with readings struggling to reach 40F Monday and Tuesday. European guidance is even hinting at a rain/snow mix, especially north of the Twin Cities. Don't rule out more slush before the daffodils arrive."
On the theory that a picture is worth a thousand words, here is how my beds look after rolling back the leaf bags this afternoon. Note that the roses still have plenty of leaves and mulch around them and the bags are right there if I want to roll them back over the plants. Incidentally, most of those leaves around the plants will get pushed back in the bags and be transported to my compost pile, when it's time to finally uncover the beds, which will probably be in 10 to 14 days, when Paul Douglas is no longer warning about slush and freezing temps.
Pruning
I always laugh when I hear someone say you should prune your roses when the forsythia blooms. Suppose it had bloomed in mid-March 2012, as mentioned above, when your roses were still covered? When the forsythia blooms really has nothing to do with when you should prune your roses. Pruning for me is a two step process. First, right after I uncover my roses (i.e. mid-April), I begin by cutting off all the dead wood, right down to where the canes begin turning green. This is a very rough, quick cut that I do with my battery-powered Black & Decker hedge trimmer. I don' t worry about rough cuts on the canes because I know I'm coming back later to make my final pruning and shaping cut. All I want to do is to take off the "overhead" of dead wood to clear the way for new growth that will come from the green canes. Once I can see that nodes on the green canes are starting to swell, in anticipation of setting new leaves, then I begin my second cuts to shape the plants and eliminate any weak, wispy growth from last year.
So, in summary, you should first cut off all the "overhead" dead wood and then, when the plants show signs of growing, make your second cut and seal it off to stop saw-fly wasps from burrowing into the fresh wood to lay eggs. I use Elmer's school glue for my sealant, which works very well and is quite inexpensive. And the forsythia may or may not have bloomed when you finish. We're talking roses here, not flowering shrubs!
Jack Falker
April 1, 2015
For folks in warmer areas, like the warmer parts of zone 6 and throughout zone 7, where the ground freezes down a few inches and then repeatedly thaws and refreezes throughout the winter, the purpose of winter cover would be the same, i.e. to keep the roses from repeatedly freezing and thawing, but in this case it would be to insulate them to prevent them from freezing in the first place. It really amounts to the same thing, however.
Given these principles, when to uncover your roses should be obvious, wherever you live. It is simply when the danger of freezing and thawing has passed. Around here, that usually occurs sometime in the first two weeks of April but virtually never in March, regardless how warm it might get for a few days. Let me give you a recent example. In the spring of 2012 we had 70 and 80 degree weather in mid-March causing fruit trees to blossom etc., but in the next week we had 10 degree weather followed by at least two weeks of below freezing weather. This caused the loss of almost the entire apple crop in Minnesota and Wisconsin and virtually the entire cherry crop in western Michigan. If you had uncovered your roses in March 2012, thereby allowing them to thaw out, you would have suffered severe damage when they froze again.
I realize that it is very tempting to uncover your roses when it first warms up in the spring. If you use the leaf bag method, which I have advocated in my blogs, you can choose to partially uncover your roses by rolling the leaf bags back but leaving them ready to replace, if the weather turns cold again. This approach allows the plants to begin thawing and to soak up spring rains, while keeping your options open for easy recovering. I would say that I use some form of this approach almost every year, especially when it starts to rain (vs snow!).
Today, April 1st, it was 82 degrees and we are expecting thunderstorms tonight so I decided to go out and roll the bags off my roses, while keeping them close-by, if I have to roll them back
Wherever you live, my suggestion is to watch the seven-day weather forecasts in early April and try to determine when your nights stay consistently above 25 F (-4 C). If you keep the mounds around your plants, even if you pull the bags back, temps down to 25 F will not refreeze your plants. If you are in doubt, just keep your plants covered until mid-April, around here. It won't hurt them.
And here's a quote from Paul Douglas' weather blog today:
"Another Relapse After a May-like temperature swoon today temperatures cool off later this week, a taste of early March shaping up for early next week with readings struggling to reach 40F Monday and Tuesday. European guidance is even hinting at a rain/snow mix, especially north of the Twin Cities. Don't rule out more slush before the daffodils arrive."
On the theory that a picture is worth a thousand words, here is how my beds look after rolling back the leaf bags this afternoon. Note that the roses still have plenty of leaves and mulch around them and the bags are right there if I want to roll them back over the plants. Incidentally, most of those leaves around the plants will get pushed back in the bags and be transported to my compost pile, when it's time to finally uncover the beds, which will probably be in 10 to 14 days, when Paul Douglas is no longer warning about slush and freezing temps.
I always laugh when I hear someone say you should prune your roses when the forsythia blooms. Suppose it had bloomed in mid-March 2012, as mentioned above, when your roses were still covered? When the forsythia blooms really has nothing to do with when you should prune your roses. Pruning for me is a two step process. First, right after I uncover my roses (i.e. mid-April), I begin by cutting off all the dead wood, right down to where the canes begin turning green. This is a very rough, quick cut that I do with my battery-powered Black & Decker hedge trimmer. I don' t worry about rough cuts on the canes because I know I'm coming back later to make my final pruning and shaping cut. All I want to do is to take off the "overhead" of dead wood to clear the way for new growth that will come from the green canes. Once I can see that nodes on the green canes are starting to swell, in anticipation of setting new leaves, then I begin my second cuts to shape the plants and eliminate any weak, wispy growth from last year.
So, in summary, you should first cut off all the "overhead" dead wood and then, when the plants show signs of growing, make your second cut and seal it off to stop saw-fly wasps from burrowing into the fresh wood to lay eggs. I use Elmer's school glue for my sealant, which works very well and is quite inexpensive. And the forsythia may or may not have bloomed when you finish. We're talking roses here, not flowering shrubs!
Jack Falker
April 1, 2015
Thursday, February 5, 2015
Climate Change Is More Extreme Up North
Readers of of my December 2014 blog: "How Winters Are Changing":
( http://theminnesotarosegardener.blogspot.com/2014/12/how-winters-are-changing.html )
will recall that national climatology statistics clearly show that climate change is more pronounced in the northern latitudes and, in particular, Minnesota. My 53-year Extreme Minimum Temperature (EMT) trend lines (1962-2014 inclusive) statistically predict that the Twin Cities area will consistently be in USDA Zone 6 (where St. Louis, Detroit and Louisville used to be), within the next seven or eight years. In fact, the EMT recorded in early January for the winter of 2015 was -11 F, which is above the trend line and within one degree of Zone 6. In fact, most of our winters since the year 2000 have been in Zone 5, with only three in Zone 4, including last year, which was an anomaly all over the northern states. Yet, the USDA persists in rating the Twin Cities in Zone 4, based on 2005 data, now 10 years out of date. Close enough for government work? Not in my book!
This week, Minnesota Public Radio published a special report on the phenomenon of northern climate change with the article: "Climate Change in Minnesota: 23 Signs". And even though many of my readers don't live in Minnesota, or even in the United States, this makes very interesting reading. I will conclude with a sentence that I have written repeatedly:
"You might argue why it’s warmer in Minnesota these days, but you can’t deny the fact that it is warmer, and that has important implications for Northern Gardeners."
Here's that excellent Minnesota Public Radio article; enjoy and let me know what you think:
http://www.mprnews.org/story/2015/02/02/climate-change-primer
Jack Falker
February 2015
jrfalkersr@gmail.com
( http://theminnesotarosegardener.blogspot.com/2014/12/how-winters-are-changing.html )
will recall that national climatology statistics clearly show that climate change is more pronounced in the northern latitudes and, in particular, Minnesota. My 53-year Extreme Minimum Temperature (EMT) trend lines (1962-2014 inclusive) statistically predict that the Twin Cities area will consistently be in USDA Zone 6 (where St. Louis, Detroit and Louisville used to be), within the next seven or eight years. In fact, the EMT recorded in early January for the winter of 2015 was -11 F, which is above the trend line and within one degree of Zone 6. In fact, most of our winters since the year 2000 have been in Zone 5, with only three in Zone 4, including last year, which was an anomaly all over the northern states. Yet, the USDA persists in rating the Twin Cities in Zone 4, based on 2005 data, now 10 years out of date. Close enough for government work? Not in my book!
This week, Minnesota Public Radio published a special report on the phenomenon of northern climate change with the article: "Climate Change in Minnesota: 23 Signs". And even though many of my readers don't live in Minnesota, or even in the United States, this makes very interesting reading. I will conclude with a sentence that I have written repeatedly:
"You might argue why it’s warmer in Minnesota these days, but you can’t deny the fact that it is warmer, and that has important implications for Northern Gardeners."
Here's that excellent Minnesota Public Radio article; enjoy and let me know what you think:
http://www.mprnews.org/story/2015/02/02/climate-change-primer
Jack Falker
February 2015
jrfalkersr@gmail.com
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