Friday, December 11, 2015

What's Happening to Winter?

The United States has just experienced its warmest autumn in history. In Minneapolis-St. Paul, temperatures in December are running about 20 degrees (f) above average; an average already pulled much warmer over 50-plus years. December in the Twin Cities is when our miriad of shallow ponds freeze, with our deeper lakes not far behind.  Not this year; what ice had accumulated has all but disappeared and what would normally be a deepening snow pack is all in the form of rain or slush.  Golf courses are open and my greening lawn looks like it could use a cutting.  And we're expecting up to an inch of rain over the weekend (which would be a foot or more of snow, if it were about five degrees colder)!

In his December 12th weather blog, my friend Paul Douglas, founder of Aeris Weather and WeatherNation says:  "... What makes our current stretch of (irrational) warmth unusual is the sheer persistence of the mild signal: day after day, week after week, month after month.... Since September 1, over 80 percent of the days have been warmer than average, according to (Minnesota state climatologist) Mark Seeley. Further, if you add in the first 10 days of December, the stretch of days from September 1, 2015 to December 10th is the warmest in state history, a remarkable run of warmth."

And here is a Climate Central map that Paul published:

Here is the address of Paul's weather blog, in case you would like to read more:

Something is going on here.  It looks like we could have a St. Louis winter (USDA Zone 7) in the Twin Cities (i.e. not below zero). And in St. Louis?  How about an Atlanta winter, and so on.  For the last several years, I have been developing and analyzing extreme minimum temperature trend lines, extending over the last 55 years, for Midwest cities, and my conclusion has been that the upper Midwest is warming faster than any other area of the country and that winters would become warmer still over the next several years.  I just didn't think it would happen quite this soon.

As a long-time, cold-zone rose gardener, I have been lightening up on my winter protection a little each year.  This year, anticipating a massive, climate-change-driven El Nino, I decided to use only compost-mounding, with no insulating leaves; a process that I might have used in Detroit (Zone 6), 40 years ago.  For several years, I have been writing that using the Minnesota-Tip winter protection procedure in the Twin Cities is a lot of unnecessary hard work and a horiticulturally unsound practice, given the trend of our winters (see my blog: "No Tipping Please").

What surprises (and amuses) me is how many people around the Twin Cities still tip their roses.  Even the University of Minnesota Landscape Arboretum still tips their roses (courtesy of the strong backs of the Minnesota Rose Society).  The reason for this, I believe, is that, in order to effectively use the "tip" method, the bud unions of hybrid tea roses must be grown at or above ground level, which, in itself, is a horticulturally unsound practice (wherever you live). So, in order to get out from under the "tip" method, you have to re-plant your bud unions deeper, which is a simple, one-time procedure (I know, I did it).  Also, old habits (and fears) die hard, but people just need to stop and recognize what's happening around them, and trust the statistical evidence.

I am also amused by articles written in local rose newsletters this past year referring to our brutally cold Zone 4 winters.  The extreme minimum temperature last winter (2014-15) was -11, only one degree shy of being in Zone 6.  Our coldest winter in many years, 2013-14 (with the horrible polar-vortex effect) had only one night falling a few degrees into Zone 4, at -23. All other night-time temps were Zone 5 or Zone 6. People who dispute these facts are probably thinking about wind chills, which have nothing whatsoever to do with plants.  See my blog "Don't Sweat the Wind Chill":

The Statistical Facts

The mathematical study of statistics focuses on the probabilities that certain events will happen (or not).  Put another way, statistical analysis can be predictive.  So, when we perform valid statistical analysis on regional winter weather, over many years, and we can see very clear trends developing, we are positioned to make predictions about future winters.  As cold-climate rose gardeners, this is pretty important because it allows us to make informed decisions about which roses to plant and how to winter-protect them most effectively.

For several years now, I have been doing 50-plus year statistical analysis on Minneapolis-St. Paul winters and comparing them with winters in other upper-Midwest cities.  The results are pretty amazing in that we can see very distinct warming trends developing. And it has become much easier to predict that these trends will continue and that we will see warmer winters going forward.  The meteorological winter of 2015-16 began on December 1st and what we are now seeing is exactly what the trend line shows we should expect: temperatures are much warmer than average, an average which itself has been pulled significantly upward over the last 55 years.  Below is my chart for the 55 winters beginning in 1961, through 2015, in the Twin Cities. What it shows is that since year 2000, all but three of our winters have been in USDA Zone 5 or higher, even though the USDA continues to rate MSP as Zone 4 (based on data that is now 10 years old).  What's most important here is the upward slope of the trend-line, which, as mentioned above, is predictive.  What the trend-line shows, if you extend it, is that MSP will be firmly in Zone 6 within the next three or four years.  Right now, based on what we are seeing, I believe we will see a Zone 6 winter in 2016, for the second time in history, and there is a distinct possibility that it could be Zone 7, i.e. not below zero at all, which would be a first.

Below is the 55 year trend line for Chicago.  Note that while Chicago has moved firmly into Zone 6, the slope of the trend line is shallower than the MSP line. In other words, while Chicago is warming, it is warming more slowly than MSP.  Interesting that Chicago's 2015 low temperature was -10, right at the      lower edge of Zone 6, while MSP's low was -11, right at the upper edge of  Zone 5; virtually no difference.

And below is the 55 year EMT trend line for St. Louis to give us some idea of what a Zone 7 winter might look like.

The differing slope of these trend lines is born out in Climate Central's chart below.  Note that the MSP area and points north along the Minnesota/Wisconsin border, as well as the Red River Valley in Northwestern Minnesota, have warmed more than any other area in the country.

Finally, let's look at NOAA's Winter Outlook for 2015-2016 and note that most of Minnesota is projected to be 50-60% warmer than average this winter. In the short term, this is attributed to El Nino ("the child"), but it is important to recognize that the phenomenon of El Nino is itself the "child" of long-term climate change. In other words, it is becoming impossible to differentiate short-term from long-term effects.  If you go back and look at all of these graphs and charts together, there is a great deal of similarity in the pace of warming in the northern tier of states.  And this is exactly what the trend lines above are pointing toward.

(credit: NOAA)

There is growing evidence that, with the extreme warming of the oceans, El Nino could become a long-term phenomenon.  Here is another snippet from Paul Douglas' weather blog, quoting a climatologist at NASA's Jet Propulsion Laboratory:

"Monster" El Nino Could Usher In Decade of More and Stronger Events. A sign of things to come?  "...While El Nino oscillates on a more or less yearly cycle, another dynamic in Pacific Ocean water temperatures, known as the Pacific Decadal Oscillation (PDO), has the potential to accelerate global warming and increase the severity of El Nino episodes, scientists said. The last time the PDO was, as it may be now, in a prolonged positive, or "warm" phase, it corresponded with two of the strongest El Ninos on record. "When you really have a monster El Nino, it could be enough to flip the PDO into a new phase for a decade or so," said William Patzert, a climatologist at NASA's Jet Propulsion Laboratory in California. "Keep your eyeballs peeled because maybe we're in for a decadal shift..." 

While this may be good news for rose gardeners, it is very bad news for our planet.  In the meantime, my advice to upper-Midwest gardeners is to plant your bud unions a couple of inches below ground and forget about uprooting and tipping your roses.  For northern-gardeners, like myself, who keep our roses firmly planted and mounded in the winter, it may be time to lighten up a little, but winter cover will still be important.  It still gets cold in Zone 6 and freezing and thawing (the roses' winter enemy) is an even bigger problem in a warmer winter environment.

Jack Falker
December 12, 2015

Friday, November 13, 2015

Protecting Roses from Vole Damage

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:

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.  This should give you some idea of how much to buy.

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:

As always, please send your questions or comments to: .

Jack Falker
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

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)


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: .

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.  

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":
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:

Jack Falker

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." 

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:

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!

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":

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 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
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:

life cycle

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 one 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.

 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:

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. 

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: .

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.

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.  

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: 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.

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": )
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:

Jack Falker
February 2015

Thursday, January 29, 2015

Composting in Winter

Composting isn't just for warm weather.  It can be a year-round activity, which, in the winter months, allows you to compost "green" kitchen scraps and lots of coffee grounds for use on your roses in the spring. Even here in Minnesota, where the ground usually freezes hard and deep in winter, compost piles will generally remain mostly unfrozen beneath the snow because of the heat generated in the decomposition process.  If you dig through the snow and open up holes in the pile, you can keep adding to it all winter.  But that hasn't been necessary here this winter, as you can see in the picture below.  Our low temperature in January was -11 f., which puts us almost in USDA Zone 6.  We had a lot of days above freezing in late December and throughout January, and what little snow we had is just about gone.

As usual, some folks in Minnesota go to extremes.  I heard a funny story in mid-November, when it was actually much colder and snowier than was in December and January.  Someone, here in Minneapolis, had moved their composting operation into their basement for the winter, in one of those fancy (and expensive) rotating drums. I guess I was kind of incredulous and asked what they were going to do with it in the basement.  The guy was kind of put out when I asked him why they just didn't leave it outside to compost naturally.  I really can't imagine having that decomposition process going on in my basement.  I just make a pile outside, where everything happens naturally, and the earthworms have a field day, leaving their castings (down deep where it's warm), year-round.

Today, I dumped about 200 lb. of Starbucks coffee grounds in my pile, along with lots of green kitchen scraps. When I opened up the pile, a cloud of steam puffed out; proof positive that the composting process is alive and well in mid-winter.  Here's how it looked, after I finished pulling the shredded oak leaves back on top.  Note the lack of snow and the two Christmas trees behind the pile doing double duty as a habitat for birds and other winter critters.  The white stake in the foreground is a terminal post for my electric fence, which comes up from underground at that point for use in the summer.  The small white stakes to the left, in the little bit of snow that's left, mark spots where I have seeded pollinating plants for stratification over the winter. This area around my mulch pile is one of several insectaries, designed to attract bees and other beneficial insects to my rose gardens. (See ).

Tuesday, January 6, 2015

Don't "Sweat" the Wind-Chill on Your Roses!

Tonight is likely to be the coldest night of winter 2015, in the Twin Cities.  Temperatures are predicted to fall to -13 F (-25 C) at Minneapolis-St. Paul Airport, which, in the context of winter history in Minnesota, is  no big deal (It's 0 F  [-18 C]  right now at 9 PM). That will put us in the upper reaches of USDA Zone 5 for the year, i.e. approaching Zone 6, when the USDA still has us listed in Zone 4 (incorrect in my opinion).

Author's note: The actual low temperature recorded on the night mentioned above (January 6, 2015) was -11 F, which should be the extreme minimum temperature (EMT) for 2015.  This puts the Twin Cities (MSP) just one degree shy of a USDA Zone 6 winter in 2015. 

But to listen to the apoplectic, Twin Cities TV weather folks creating "shock and awe" among their listeners, the real news is that wind-chills are going to reach a "dangerous" -30 to -35 F (-34 to -37 C) by tomorrow morning.  By doing this every day in the winter, they have created the idea among a very large number of people that temperatures are much colder than they really are.  In point of fact, wind-chill is only relevant to the cooling of the exposed flesh of warm-blooded animals (with no fur like us, unless you grow a beard). It has nothing to do with the temperature of cars or houses or, most importantly, plants, which in our case means ROSES! (For a full explanation of the effects of windchill on roses, see the quotes below from my wind-chill blog of last January).

Looking at it another way, if you're foolish enough to run around outside in your birthday-suit tomorrow morning in Minneapolis you're going to freeze your "you-know-what" off in the "relative" -30 to -35 F wind-chill, because of the effect of the cold temperatures on your exposed flesh, plus the wind which doesn't allow your body to warm itself. But if you dress warmly with a coat, hat, gloves, ear-protection and maybe a scarf over your nose, you have nothing to worry about, except the real ambient temperature of -13, which is cold enough, without trying to make it sound worse.

Here a couple of images of one of my Buck Earthsong beds taken last year at this time, when we had a lot more snow than we have now, which was a good thing then:

And here are several quotes from my article "How Windchill Affects Roses" from last year at this time:

First, from a National Weather Service article:

"Wind chill is the term used to describe the rate of heat loss on the human body resulting from the combined effect of low temperature and wind.  As winds increase, heat is carried away from the body at a faster rate, driving down both the skin temperature and eventually the internal body temperature.  While exposure to low wind chills can be life threatening to both humans and animals alike, the only effect that wind chill has on inanimate objects, such as vehicles, is that it shortens the time that it takes the object to cool to the actual air temperature (it cannot cool the object down below that temperature)."

And from a Kansas State University article:

Plants Don’t Care if the Wind Chill Tanks

"When wind chill temperatures plummet, gardeners chafe about their landscape and fruit plants' odds for survival.  Some gardeners worry too much.... Cold can be a killer if people are growing marginally hardy plants or if air temperatures drop well below what's usual where they live.  Hard freezes are particularly destructive when plants aren't fully dormant.  But cold and wind chill aren't the same thing.  Wind chill only affects warm-blooded animals -- including people.  It's an indexed, scientific measure of how wind speed and air temperature combine to impact animal heat loss.... We know, for example, that our heat-loss rate will speed up as the air temperature drops.  The faster the wind is blowing, however, the more dramatic that heat loss is going to be .... Wind chill has no meaning for plants.  Unlike warm-blooded animals, they don't try to maintain a particular body temperature year-round".

And another:

"Of course, we know that  roses feel the winter cold and die back according to the level of protection afforded them.  And winter-winds do, of course, have an effect on that die-back, desiccating the canes, but the important thing to understand is that wind does not make a plant "feel" colder than the actual temperature, even though it shortens the time it takes for the plant to reach that temperature.

And this one is important:

Here's an example: Suppose that the ambient temperature is 35 F and the wind is blowing 30 MPH. According to an NWS  chart, the wind chill is 22 F.  So are your roses freezing?  Or, better yet, are the puddles in your garden freezing?  Of course not, because the freezing point of water is 32 F.  However, if you go out in your garden without a hat and jacket, you will feel like it is 22, not 35, because of the combined effects of the cold temperature and the high wind on your flesh."

And here's that whole article from last January:

Let me know if you have any questions.  I'll be safely bundled up tomorrow morning when I go outside.

Jack Falker