Sunday, December 21, 2014

How Winters Are Changing

Climate Central (CC), an independent organization that surveys and conducts research on climate change, recently published a series of  maps showing the relative extent of climate change in all regions of the United States. What's most notable about these maps is that the northern tier of states has experienced the most winter-warming since 1970, and that the upper-midwest, especially Minnesota, has warmed more than the any other area. Here's that article:

What really jumped out at me when I saw CC's maps was that they show exactly (and not surprisingly) what my own trend-line graphs of Extreme Minimum Temperatures (EMT) indicate, which is (1) that the whole northern tier of states has gotten significantly warmer and (2) that the further north you go the sharper the change.  The difference between CC's work and mine is that the Minnesota  Rose Gardener graphs cover a longer period, i.e. since 1962 vs.1970, and that my graphs are dynamic, in that the trend lines, being statistically valid, are predictive of the future.

Here is CC's map of the United States:

Note that the upper-midwest generally has warmed more than the rest of the country and that the areas around and just north of the Twin Cities, and in the northwest corner of Minnesota, have warmed more than just about anywhere else in the country (my upstate NY and New Hampshire readers will be happy to note they are paralleling the upper-midwest).

This is very clear when you look at my 53 year EMT trend-line graph for the Twin Cities.  Note the relatively sharp slope of the line and how it points upwards to USDA Zone 6.  I will show several other cities' EMT graphs below, which show definite warming, but with shallower trend lines than Minnesota, just as the CC map shows.

Here is a regional close-up of the upper-midwest from CC's article:

And now let's look at the EMT chart for Milwaukee to see the difference in the slope of their warming trend-line:

Note that the slope of the trend-line, while definitely upward, is not quite as sharp as the Twin Cities' line and, while they've had two winters solidly in USDA Zone 7 in this decade, the line predicts that it will be quite a few years before they move into Zone 7.

Here is Detroit, which has now crossed into Zone 7, as predicted by the trend line, albeit with a very shallow slope over quite a few years.

Here is CC's regional close-up of the Ohio Valley:

And here is my EMT graph of St. Louis, which has moved solidly into Zone 7, with a fairly sharp upward trend:

And here is Chicago, which perennially was in Zone 5 but now has moved solidly into Zone 6.  Note that the slope of its trend line is very similar to Milwaukee's, which should be no surprise, but they too are quite a long way from being consistently in Zone 7.

Finally, here is Indianapolis, which has a trend line a bit shallower than Chicago or Milwaukee, but the line projects that it is almost in Zone 7 (and actually had a Zone 8 winter in 2012).

So What Happened Last Winter?

That's a perfectly logical question, in the face of all the trend line evidence of warming.  Most climate scientists believe that the "polar vortex" phenomenon we experienced last year was (or is) a product of climate change and that it is unlikely to repeat itself with regularity.  However, that is certainly not to say that it won't happen again or that we might not see variations of it.  Note in the graphs above that last winter was a big departure from all trend lines, especially in some of the warmer midwest cities like Detroit, St. Louis and Indianapolis. With a developing El Nino, which is also a child of climate change, it seems unlikely that we could see another major vortex incursion in the winter of 2014-15.  For a more detailed explanation of the polar vortex and its presumed causes, please see my October 2014 blog: "Winter Protecting Roses in a Climate Change Environment". .


Finally, I would like to emphasize the statistical validity of the trend-lines generated on the graphs in this article.  As mentioned earlier, these trends are both predictive and dynamic, in that you should be able to extend them into the future with a fair degree of accuracy, regardless of one year anomalies in either direction.  For example, it is logical to conclude that the Twin Cities will see more winters in Zone 6 than in Zone 4 in coming years and that, within the next seven or eight years we will see consistent Zone 6 winters.   This can be clearly seen on the St. Louis graph, as it progressed along its trend line to where it crossed into Zone 7.  And the same can be seen on the Detroit chart, although its change was more gradual and over more years.

Having said all of this, I am not implying that winter-protecting roses isn't important to prevent the inevitable freeze-thaw cycle.  Rather, I am saying that extreme measures, such as the Minnesota Tip, are unnecessary, if sensitive roses are properly planted with bud unions below ground.  Please see the article cited above, as well as my September 2013 article "Winter Protecting Your Roses" for more complete explanations: .

Jack Falker
December 2014

Monday, December 8, 2014

"Bugs and Roses"

This is part two of my July 2014 article "Controlling Spider Mites and Thrips on Roses Without Insecticides-- Part One".  In case you haven't seen it, here's that article:

The underlying purpose of these two articles is to demonstrate that attracting, introducing and nurturing beneficial and predatory insects to control common pests like spider mites and thrips is both possible and desirable in a rose garden.  I finally realized, after many years of spraying everything from organophosphates like Orthene, neonicotinoids like imidicloprid (Merit) and pyrethroids like Demand CS (which is what I thought I was supposed to do to control everything from aphids to Japanese beetles), that what I was really doing was wiping out naturally occurring beneficial and predator insects.  For example, I suddenly realized that I no longer was seeing lady beetles and lacewings, which are natural predators for spider mites.  It's no wonder because, instead of tediously picking Japanese beetles off my plants and drowning them in soapy water, I sprayed them with Demand CS, which works really well, but also wipes out all other beetles (like lady bugs) and just about every other predatory insect in the garden.  As a result, I ended up with a massive infestation of aphids (something I hadn't seen in many years) because I had destroyed all their predators, in my efforts to deter Japanese beetles.

Then, early in 2014, my compatriot-rosarian Paul Zimmerman mentioned a new book by Jessica Walliser, "Attracting Beneficial Bugs to your Garden", which changed my way of thinking about controlling insect pests in my gardens.  Here's a link to that book, which is available both new and used on Amazon:

Well, after reading Jessica's book multiple times, I decided I had to try what she advocates, and I learned a lot.  First, the good news:  I was very successful in controlling thrips without insecticides all last summer and, as a direct result, beneficial insects, including honey bees, bumble bees, mason bees, syrphid flies, lacewings and predatory wasps have flourished, on their own.  Second, the relatively bad news: spider mites were harder to control than I thought, when I wrote my July article, above.

I washed my roses at least every other day and I just couldn't get rid of the spider mites altogether.  Just when I thought I had the upper hand (as I did in July when I wrote the article) they would come back, not to the extent where I would see a lot of webbing, but just to where they would appear on new growth. If you were to look with a magnifying glass at the wilted leaf just under the bud in the picture below, you would find just a thread or two of mite webbing.  So the wilted leaf is a tell-tale sign; something it has taken me a long time to understand.  Those leaves die and become "crispy", as the mites multiply and move on to other new growth. I was able to control the mites by cutting off that leaf stem and washing the plant, but they continued to pop up elsewhere on other new growth, no matter how much I washed.

I really didn't want to use a miticide because I had imported large quantities of predatory mites (at least 100,000 cucumeris and fallacis mites) from California and I wanted them to do their job on both the mites and thrips, before applying a miticide, which would likely take down most of the mites, including predators.  I made it until late August without using anything but water, but finally I had to do something because even my most resistant roses were succumbing to blackspot from the constant washing.  In August, I made one application of Floramite and that took care of the spider mites.  I won't know until spring if I killed all the predators (Fallacis mites are supposed to be hardy enough to overwinter in Minnesota) so we'll have to wait and see.  I'm not giving up on this, however.  Next spring I will start washing earlier and, if I can't control the mites with existing predators, such as lady beetles, which I didn't have in 2014, I will reintroduce more predatory mites.  I still believe it will work if I get enough predators on the plants

Thrips (both singular and plural, i.e., one insect is called a thrips)

Given the persistence of spider mites, I was pleasantly surprised to find that I was able to control thrips with the beneficials I was able to introduce and/or attract to my garden this summer.  Here's what a Carefree Beauty bud with thrips running around in it looked before my beneficials got to work.  By the way, any bud that looks like this gets plucked and disposed of someplace where the thrips can't fly back into the garden. That's the first line of defense when you're not spraying insecticides.

As long as you don't spray things that kill them, natural thrips predators, such as minute pirate bugs and syrphid flies are fairly easy to attract to the garden with plantings, such as oregano, yarrow, alyssum and cosmos.  And predatory mites can be imported from an insectary, such as Rincon-Vitova in California.  In talking to Jan Dietrick, who runs Rincon-Vitova, I also learned that beneficial nematodes released in the soil of each rose bed will feast on the pupa of thrips, eliminating something like 80% of them before they become active on the plants.  I ordered millions of the nematodes Jan recommended, as well as thousands of cucumeris predatory mites and 500 minute pirate bugs, in addition to 500 lady bugs for spider mite control. By the way, these beneficials aren't terribly expensive, compared with what I've been spending on insecticides.  However, the required overnight shipping is quite expensive so it's advisable to combine as much as you can in one shipment.  Here's Rincon-Vitova's website:

I'm not sure exactly what did the trick on the thrips but, after they got off to a head start on me (see the picture above), I was able to control them from mid-summer onward.  I'm pretty confident that the nematodes were effective and I could see the syrphid flies, which arrived in droves, probing around in the flowers, so I believe the combination of those two worked.  The minute pirate bugs arrived too late to become well established, but I'm sure they will be around next summer, and I'm not sure about the predatory mites because they were too hard to see but I saw enough of them with my magnifying glass to know they were there.

Here's an interesting statement from an article on thrips by Applied Bio-Nomics,  the producer of the predatory mites I purchased from Rincon-Vitova:  "The first thing to know is that  I do not believe that  a single thrip has died from an insecticide registered against thrips for the past three 
 years  .... I will bet you that they died from the soap effect  of the spreaders and  the stickers rather than the active ingredients. So,don’t even think about using chemicals against thrips.... Another even more important reason not to use chemicals is because there is now considerable research that shows that sub-lethal chemical attacks actually induce the thrips to lay more eggs. "
You can find this article and several other equally interesting articles on Applied Bio-Nomics' website:

So, according to this expert, a chemical like Conserve SC (spinosad), the insecticide of choice for thrips, doesn't kill thrips, it just kills the beneficials like syrphid flies and minute pirate bugs that attack thrips.  This is completely opposite to what we have been taught to believe as gardeners.

Insectary Effects

Here's how a little insectary corner of one of my rose gardens looked last summer, with oregano, bachelor buttons, cosmos, dill, yarrow and a few other things to attract beneficials (Buck's Prairie Harvest is to the right).  When I took this picture, this little garden was teeming with wasps, bees and other beneficial insects that were nowhere to be found in my garden last year.  The idea of doing this, as well as directions on what to plant to attract various beneficials, came directly from Jessica Walliser's book, mentioned earlier.  I plan to expand my insectary efforts next year, which will include removing several more roses to make room for more beneficial bug-attracting plants.  In short, this really works!

Here's a picture of a bumble bee on one of my Earth Song plants last summer. I was really amazed at how many bees showed up in my gardens after I stopped spraying. 

Here's another bumble bee on one of the many sunflowers I planted last summer to attract beneficials.  I have no idea where all the varieties of bees (including many honey bees) came from but I did notice, with great interest, that the bumble bees were going in and out of a nest they had made alongside a drain pipe, just a few feet from where I had planted a stand of sunflowers to attract them.  No coincidence there!

One of the most important things Jessica Walliser talks about early in "Attracting Beneficial Bugs to Your Garden" is the need to be patient.  When there is a large infestation of insects like aphids or spider mites, it takes  time to build up enough predator mites and insects to feed on them.  I believe that's what my experience was with the spider mites this summer because I had killed off so many beneficial predators over the years, especially in my efforts to control an infestation of Japanese Beetles, which was especially bad in 2012.  I have written several articles about that effort, but I now recognize that the use of the pyrethroid, Demand CS, which is very effective in deterring the beetles, comes at the price of eliminating many beneficial insects (about which a knowledgeable rosarian from the TCRC, Sue Youngdahl, gently reminded me at the time). I'm not going to use it again in my garden, as well as other insecticides, with the possible exception of an occasional miticide, as I did this summer but would really like to have done without.  However, it is understandable that large public gardens and commercial growers do not have that luxury in their need to control Japanese beetles on a large scale, where picking them one at a time off the plants would be impossible (and those bugs are really awful and terribly destructive).  For example, I noted that the University of Minnesota Arboretum was using a pyrethroid in their rose gardens last summer, which is completely understandable.

What I achieved in one growing season was remarkable and these results have made me want to try even harder next year.  Nature is exceptionally responsive to our efforts to protect it, and my own most important lesson is that patience is everything, as we change our practices.  The rewards are well worth the inconvenience and extra effort.  I'll have more to say about  this as we go along, so stay tuned and feel free to ask questions.  We can learn together!

@mnrosegardener (Twitter)

December 2014

Saturday, October 4, 2014

Winter Protecting Roses in a Climate-Change Environment

Here is a PowerPoint presentation I made to the American Rose Society, North Central Division convention in the Wisconsin Dells on September 13th of this year.  Some of the presentation is a reprise of my March 2014 Blog: "What the Heck was Wrong with This Winter" and my September 2013 blog: "Winter Protecting Your Roses"

For the most part, the slides speak for themselves.  However, where explanation and comments are needed, I will fill in with some of the remarks I made during the presentation.

So here we go....

This is a picture I took of my nicely winter-protected Earth Song bed on Christmas Day 2013, right after we had received 8 inches of new snow cover, thereby providing the best natural winter protection of all.  Here in Minnesota, we seldom have to dream of a white Christmas!

But our winters are definitely getting warmer, as we shall see.

Below is my recently updated Minnesota climatology chart showing the Extreme Minimum Temperatures (EMT) for the last 53 years at MSP airport.  This is the statistic the USDA uses to determine the cold zones.  As you can see, the Twin Cities are no longer consistently in USDA Zone 4b.  As a matter of fact, there have only been three nights in Zone 4 in the Twin Cities, since 1999!  That hardly puts us in Zone 4 and, as you can see, the mathematically determined trend-line has an upward slope of about 25 radian degrees. If you project that trend-line off the right side of the chart, it would appear that the Twin Cities will begin to see more winters in zone 6 than in zone 4, within the next five years.

The most recent USDA charts were released in 2012, based on 1976-2005 data.  In other words, their data, prepared for them by Oregon State University, was already seven years old when they released it and is currently nine years old.  Those seven winters were some of the warmest ever recorded, which made the USDA data invalid when they released it.

Good enough for government work?  Not in my opinion.  We just have to think for ourselves, given the data shown below. 

Note that for all of the cities shown below the winter of 2013-2014 was unusually cold, pushing them down into zones that they had not seen in several years.  Cities like Chicago, Detroit, Indianapolis and St. Louis were especially hard hit, relative to the much warmer EMTs  to which they had become accustomed in recent years.  Look at Indianapolis, for example: the winter of 2012 had been zone 8 and 2013 had been zone 7, when the bottom fell out  in 2014, dropping them to zone 5.
This is a much bigger swing than the Twin Cities experienced and, even though we experienced a near record number of nights below zero in 2014, most of them were in zones 6 and 5; not a huge variance.

Milwaukee is rated at zone 5b, but they have had only five EMTs in zone 5 since 1999.  The rest of the years have been in zone 6 and zone 7; go figure.

Chicago, which was classified in zone 5 for many years, is now classified in zone 6, which is correct, but looking at the Milwaukee and Chicago maps together, it's hard to understand why Milwaukee, just a few miles north is not classified similarly, given the data of the last several years.  Looking at the slopes of their respective trend lines (Milwaukee's is steeper), both cities will likely see many winters in zone 7 over the next several years.

Look at Indianapolis: going from zone 8 in 2012, to zone 7 in 2013, to zone 5 in 2014; a big surprise for gardeners there, who aren't accustomed to extensive winter protection.

Detroit, which has perennially been in zone 6 ( I grew up and lived there until age 37, and can't remember anything colder than -10) has had eight winters in zone 7 and one in zone 8 since 1999. They've had only five winters in zone 5 in the last 53 years, and last winter was one of them.  This is a much bigger variance than seen in most other Midwest cities.  The only thing we ever did to our roses, when I was growing up, was to rake some leaves on the beds.  That sure didn't work last winter, when both Lakes Michigan and Huron froze all the way across.

Like Indianapolis, St. Louis' winters dropped two zones from 2012 to 2014; almost making it three zones to zone 5!  Suffice to say that no one there was ready for that to happen last winter.

What happened was an incursion of the "polar vortex" a phenomenon that had never been seen in the U.S. to the extent that it was in 2014. Note, in the two graphics below, that unusually warm air, both to the west and east of North America formed a "pincers" around the normal polar vortex, a cyclone of super-cold air rotating tens of thousands of feet above the north pole (south pole too) tipping it over into central Canada and the Midwest USA.  Note, in the second graphic below, that it also happened in China and eastern Siberia, which you would expect, but something that was not reported here.

Note that it was as warm in England and Western Europe (just to the right of Greenland on the great circle map below), on February 27th, as it was along the Gulf Coast of the United States; pretty amazing.

Be sure to also read my blog: "Winter Protecting Your Roses", written in September 2013:

Saturday, September 20, 2014

A Potassium Feast for your Roses

For those of us in the cold zones, i.e. USDA zones 3-6 (and maybe zone 7, given last year's polar vortex incursion), 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 last year at this time:

"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.

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.  To help folks around the Twin Cities get started easily this year, I have made up some small bags (about 6 lb.) that I will provide at my cost. Send me an e-mail to: or call my cell phone: 612-385-6226. (6 lb. of muriate of potash lasts quite a while at 1 tsp/gallon.)

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% sulfate.  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 this 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

Friday, July 25, 2014

Japanese Beetles and Roses--2014 Season

Well, it's late July and the Japanese Beetles (JBs) are just about at their peak here in Minneapolis. I would say we're seeing more than last year but not nearly as many as in 2012.  So does that mean it's getting better or worse?  In 2012, a golf course greens keeper told me that most golf courses in our area were using large amounts of imidicloprid (Merit) to protect fairways and greens from the JB grubs.  I attributed the downturn in last year's JB crop to be the result of that practice, since I have two golf courses within a mile of me, which is well within the JB flying range.  My best guess is that the golf courses probably used less imidicloprid in 2013 because of growing awareness that it is the most widely used of the neo-nicotinoid family of insecticides, which have been strongly implicated in bee colony collapse disorder and have been banned in Europe (imidicloprid is made by Bayer in Germany).  Also, I would assume there was less incentive to put it down on the golf courses, with such a sharp reduction in JBs during 2013.  Anyway, they're back again in force, so it's a good time to look again at the best ways to control them.

Here is a key passage from my 2012 article "The Beetles Are Coming, The Beetles Are Coming", as revised in January 2013:

.... 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 “secret” 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 soap-water.  I’m as squeamish as the next guy or gal 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 (Maxwell House), 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 many days, through thousands of JBs, there is some pleasure in watching the little demons meet their end, knowing that every JB I 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.  

The main point here is that insecticides are really not the best answer for controlling JBs.  There is a very effective pyrethroid, that I mention in the article, but it also kills insects like lady bugs (they're beetles too) and other beneficials that eat aphids and thrips.  When you kill them off, you start a vicious cycle of insect infestation, which is far more difficult to control and a lot more work than a few weeks of drowning JBs!

I just issued a blog: "Controlling Spider Mites and Thrips on Roses Without Insecticides" .
So, if I were to spray a pyrethroid on my roses to deter the JBs now, I would negate all the work I describe in this article to introduce predatory mites and attract beneficial insects to my gardens.  I have not seen a single aphid in my gardens this summer because of the beneficials.  Last year, when I aggressively sprayed the pyrethroid for the JBs, I ended up with a major infestation of aphids.  Obviously, I had taken out all their enemies, so then I had to spray another insecticide to stop the aphids.  That's a vicious cycle, and all because I didn't want to drown JBs, i.e. lazy gardening.  What impresses me, however, is how well the beneficials have come back this summer, now that I'm not killing them off.  I really don't want to do that to them again.

As I meander through my rose beds, in the morning and evening (the best times), picking the beetles off the leaves and flowers and popping them in the soapy water, I carry a scissor and a bucket with me for disposing of the deadheads and damaged leaves that I cut off the roses, at the same time. In other words, I find that passing through the gardens several times a day causes me to do a better job of caring for my roses.  That side-effect of the JBs has become an important  part of my gardening routine.

So could JBs actually have a positive effect on a rose garden?  Well, that's a stretch!

Let me know if I can help.

Wednesday, July 23, 2014

Controlling Spider Mites and Thrips on Roses Without Insecticides-- Part One

Author's Note: I started writing this blog in early June, when I decided that I was going to try and get through this growing season without insecticides, in order to attract and keep a population of beneficial insects in my gardens, which would attack the undesirables,i.e. two-spotted spider mites and thrips.  Frankly, I didn't want to publish this and then find that my methods weren't working. Well, here we are more than a month later and I'm very pleased to report that the only thing I've sprayed this summer is lots of water for the spider mites; plus I've imported from California large quantities of predatory mites (at least 100,000), nematodes (millions and millions), lady bugs (500) and minute pirate bugs (500) to attack both spider mites and thrips.  Bottom line: It's working!  In part one, I'll deal with spider mites, which are fairly simple to control with water and predatory mites, and then, in part two, thrips, which present a more complicated challenge.

Two-Spotted Spider Mites 

I've always had problems with spider mites. I've tried just about everything to get rid of them, but they just keep coming back.  I've spent a lot of money spraying miticides/ovicides, only to find that the mites are either not completely taken down, or there are still enough eggs hiding in and around the plants to start up new generations.  I have also known for years that water, sprayed in a sharp stream on the underside of plant leaves, is very effective in removing mites.  Once you knock the mites off the plants, they can't get back on and they die, so what's left on the plants are the eggs for the next generation.  I've been reluctant to do this, however, because water-washing 100-plus roses every three or four days (to hold down new generations of mites) has always seemed like a lot of work, plus it flies in the face of the conventional wisdom of not top watering roses.  Well, experience has taught me otherwise, and here's why.

I do a lot of propagation work, both with stem cuttings and air layering, and consequently I always have several plants under lights during the winter.  These plants always develop spider mites, which means I'm bringing mite eggs into the house on these cuttings/air layers.  And that proves that the miticides/ovicides I've been using aren't working.  I always wash these indoor plants with sharp streams of water in our laundry sink (which is messy when the plants start getting big) but, as long as I'm diligent about washing every three or four days, the mites go away.  So, I know washing works and I asked myself why I didn't just do that outside?

Miticides are expensive, especially those that contain ovicides to try and kill the eggs.  For example, an 8 ounce bottle of Forbid, a miticide/ovicide, which is the best product I've used because it's translaminar, meaning that it penetrates to the bottom of leaves to kill both the insect and its eggs, sells for $245, on sale from $289 at Rosemania.  That's more than $30 an ounce!  It works for a while, after a couple of applications (which it ought to at that price), but, as mentioned above, I've proven that the eggs are still there. I've also used Floramite, which has an ovicide in it but is not translaminar, and it really doesn't compare with Forbid in effectiveness, so it really has been unsatisfactory for me.  It's not cheap either, on sale at $119 for 8 ounces, down from $125, at Rosemania. Avid, which I used for many years, is just a miticide, with no control for the eggs.  This one needs to be sprayed every three or four days to kill successive generations of mites, and it works, if you are diligent, but really it does essentially the same thing as water, sprayed in the same regimen.  Avid isn't cheap, either, at $100 for 8 ounces.

The over-riding downside of these products is that they are relatively dangerous. You must wear protective clothing and you must wear a mask so you do not inhale them.  This is no joke. I had a bad experience, which caused lung problems for years.  Thankfully, it has gone away, but now I won't spray anything (except water) without a full-face 3M respirator and a Tyvek suit.  See my post on protecting yourself:

So, I asked myself this spring, after successfully controlling mites indoors with water all winter: Why don't I substitute a little sweat equity for all those expensive and dangerous chemicals on my shelf and just diligently wash the spider mites off my roses every couple of days this summer?  So that's what I've been doing for the last couple of months and I've been quite successful, although I'm still finding pockets of mites, as evidenced by a bud bending over here and there, which is a sure sign something is attacking the plant (see picture below).  On inspection with my magnifying glass, I invariably find webs and, after plucking that bud, I give the plant a special washing, paying special attention to all the buds and new growth on the plant.  This one, for example, had just a few webs on it but the damage had already been done.  This is also also a symptom of thrips or rose midge.

In the July-August 2014 issue of "American Rose", Rich Baer refers to this problem as "Funny Bud" and his "nonscientific conclusion" is that: "Funny Bud occurs when the normal development of the petiole is altered and the cells that are dividing to produce the petiole go astray and produce a leaf."   I think Rich is a great photographer but I beg to differ with his "nonscientific conclusion" here.  My experience is that funny bud is always an indication that the rose is under attack by insects (which, of course, could be what's making the petiole go astray).

Bottom line: Never leave a bud like this on the plant; get rid of it in a way that the insects can't spread. That's especially true of thrips and midge which have wings and will find their way to another plant.  Funny buds never produce good flowers and they need to go.

How to do it

The other day, I asked my good friend Susan Fox, rosarian par excellence in southern Illinois, what she does for spider mites.  After kind of growling into her cell phone, she said:  "I just spray them with a sharp stream of water; that's the only thing that really works.  None of the expensive miticides do the job as well as water".  I couldn't have said it better; so we're on the same page!

There's no secret about this either.  There are three or four mentions of this method in the July-August "American Rose" alone, including a quote from me in Susan's article: "Some Like it Hot".

I use several water spraying methods.  I have a great water wand that was advertised in the "American Rose" for many years by Walter Vinton in Springfield, MO.  It sprays a high-pressure fan of water directly upward, which allows me to get under each plant and work upward to the buds.  Unfortunately, Walter passed away and the product is no longer available. Here's how it looks:

I also use an old fashioned brass twist nozzle that is available in most hardware stores (as opposed to the big box stores, which seem to have lost track of such things).  Usually the sprayer head on watering wands is removable and you can replace it with a standard brass nozzle like this:

For my readers in Minnesota and Wisconsin, I found this wand at Menard's in Minneapolis ($7.99) and it actually makes a pretty good mite blaster, with the hose nozzle attached.  It is particularly effective in spraying the tops of the roses, i.e. the buds and new growth, and you can do it from a distance, if you see some evidence of mite damage.  You can vary the intensity and, with the curved tubing, you can also direct a sharp stream from the bottom of the plants (see photo below):

Early in the season, when the mites first appear, it's important to wash your roses at least every couple of days, for a few weeks, until all signs disappear. You can then revert to every four days or so, while paying special attention to hot spots, where mites seem to be the hardest to control.  Theoretically, the mites regenerate every four days from the eggs left on the plants and in the soil.  Remember, however, that there are likely to be several generations of spider mites in your garden, so they could be regenerating every day for a while, until you get them under control.  If you keep washing repeatedly, you should be able to kill off all succeeding generations, such that fewer new eggs are being laid.

And remember, at the same time, you're also washing aphids off your plants.  That's a plus!

Make no mistake, it's a lot of work to wash 100+ roses every two days, but it does ease up after a while, as you start to get control of the majority of the roses.  Hot spots on certain plants will remain and those need to be tended to every day or two.  If you see wilted or "crispy" leaves on new growth, that's a sign that mites are present (see a hot spot plant below).

I aggressively wash these wilted leaves and then all the new growth around them.  Then I pluck those leaves and throw them away.  They will die and become dry or "crispy", so there's no point in leaving them on the plant.  They will definitely not recover.  Note that the leaves below show no signs of mite damage; they are just on the new growth, so that's where I concentrate my washing efforts. The folks at Rincon-Vitova Insectaries in Ventura, CA, where I acquired my predatory mites, say they work from the bottom of the plant upward, forcing new generations of spider mites upward onto new growth.  That seems to be exactly what I'm experiencing, as in the above photo.  So all of my washing is on the new growth at the moment because that's where the damage is continuing; plus I don't want to wash off the predatory mites at the bottom of the plants.  Unlike spider mites, however, they can climb back on the plants and get back to work!

The downside of washing roses that are susceptible to black spot is that the fungus spores will eventually find their way onto the leaves from all the splashing.  Even though most of my roses are disease-resistant (by design), I am beginning to see black spot, here and there, in the third week of July, after two months of washing.  So, I'm about to spray a first round of Mancozeb (Manzate), which is the only fungicide that actually kills the spores, as opposed to just "controlling" them.  This will be the first time I will don my Tyvek suit and full-face respirator this year, so I'm quite pleased with the results of my no-spray efforts thus far.

For more information on treating black spot please see my July 2012 blog "There's a Fungusamongus":  .

Finally, the upside of washing your roses on a hot summer day is that you get a little wet.  It always reminds me of running through the sprinkler when I was a kid; a very long time ago.  So it's fun work :)

Please feel free to ask questions about anything, either here on the blog page or directly by e-mail to: .

In part two of this article, I will talk about my experience controlling thrips with beneficial insects and nematodes this summer.  It's working!

Good washing... and stay tuned to the Minnesota Rose Gardener.


Wednesday, March 5, 2014

What the Heck Was Wrong with this Winter?

For openers, before we dig into why it's been so cold in the Midwest this winter, let's take a look at what's really wrong with this winter around the world.  Here is a picture that Paul Douglas, Founder and CEO of WeatherNation, received from his great aunt, Eva Fels-Huber, in Cologne, Germany, along with her description of this winter in Western Europe:

"We are still waiting for winter to arrive.  We had spring-like temperatures since December 10th, 12C (53F) every day.  The birds are singing; my roses started blooming in mid-January." 

After Paul sent me this picture from his aunt, I sent an e-mail to a friend in Germany and asked her what their winter had been like this year.   Here is her response: 

“As for the winter here: we live between Mannheim and Heidelberg and didn't have winter at all. My sister in Bavaria said: some snow showers, that was it. Friends of ours in Eastern Germany said about the same. It is colder there than here, but no winter really.
In the middle of February I saw in Heidelberg meadows full of blooming daisies.  Now when you walk or drive around: everywhere daffodils and bushes and trees in yellow, white and pink.”

This is more the norm around the world than our cold weather in the Midwest.  Consider this statement from Paul Douglas' blog in the StarTribune:

"...Earth had its fourth warmest January.... According to NOAA, the combined average temperature over global land and ocean surfaces for January was 54.8 degrees Fahrenheit, which was 1.17 degrees above the 20th century average.  Using different analysis methods, NASA also concluded that Alaska had its third warmest January.... China had its second warmest January on record, and France tied with 1988 and 1936 for its warmest January."

Enter the Polar Vortex

So, tell that to gardeners in Minnesota and the whole Midwest.  If the earth is warmer than normal, how does that account for what seems to be one of the toughest winters in Midwest history? Here's a January 6th quote from Andrew Freedman of  the climate think-tank, Climate Central, that speaks to that question:

"Scientists said the deep freeze gripping the U.S. does not indicate a halt or reversal in global warming trends, either. In fact, it may be a counterintuitive example of global warming in action. Researchers told Climate Central that the weather pattern driving the extreme cold into the U.S. — with a weaker polar vortex moving around the Arctic like a slowing spinning top, eventually falling over and blowing open the door to the Arctic freezer — fits with other recently observed instances of unusual fall and wintertime jet stream configurations.

"Such weather patterns, which can feature relatively mild conditions in the Arctic at the same time dangerously cold conditions exist in vast parts of the lower 48, may be tied to the rapid warming and loss of sea ice in the Arctic due, in part, to man-made climate change.

"Arctic warming is altering the heat balance between the North Pole and the equator, which is what drives the strong current of upper level winds in the northern hemisphere commonly known as the jet stream. Some studies show that if that balance is altered then some types of extreme weather events become more likely to occur."

There is no question that the intrusion of the Polar Vortex is producing one of the worst winters in a long time for the Twin Cities and around the Midwest, including cities like Chicago, Detroit, Indianapolis and St. Louis. As a matter of fact, places like Detroit and Chicago have had worse winters, relatively speaking, than the Twin Cities. More about that later.  The real problem with the winter of 2013-2014, however, is not the depth of the cold, but the extent and continuity of it. We have currently had 50 below zero nights here and several more are predicted, which probably will put us in at least fourth and possibly third place, historically, for number of below zero nights in a winter season (the record is 60 in 1874-75, which we probably won't reach).

But it's important to note that we have had only one night this winter with USDA zone 4 cold.  It was -23 on January 6, 2014, which by no means was record cold for us.  In the 53 winters since 1962 the lowest temperature recorded has been -34 in 1970.  The rest of our below-zero temperatures this winter, despite how bad they felt, have been in zones 5 and 6.  Here's the breakdown: One below zero night in zone 4, 11 in zone 5, and the other 38 in zone 6.  So, while some people (especially some of  the TV weather people droning on about wind chills) would like to call this a record cold winter, it really isn't; it's just very long and miserable. And honestly it's wearing very thin with me, not unlike last winter, which was warmer, but also very long. Please read the conclusion of my blog: "How Winter Affects Roses" for my take on how an unreasonably long winter negatively affects roses:

People in Minnesota are so naturally self-effacing about winter that they tend to think this is happening only to them: "Uff Dah, it's why we tip our roses, don't ya know" Not! As noted above, we have had just one night in zone 4 (and just barely), considering that 12 of our winters since 2000 have been in zone 5.  With that in mind, let's take a look at how other Midwest cities have been affected.

  • Detroit and Ann Arbor, where I grew up and went to college, have almost always been in zone 6, in the lee of the Great Lakes. Since 2000, six of Detroit's winters have been in zone 7 (i.e. not even below zero) and the rest in zone 6. This winter, their low temperatures have been -14 and -12, i.e., two nights in zone 5; twelve nights in zone 6, and the rest in zone 7.

  • Chicago, which has had all but one of its winters in zone 6 or above since 2000, had a low of -16 in January, with a grand total of four nights in zone 5.  That's a bigger variance than either Detroit or the Twin Cities.

  • St. Louis, which has been in zone 7 every year since 2000, with one exception when it was in zone 8, saw a low of -8 this winter, with a total of four nights in zone 6; a big variance for them.

  • Indianapolis, which has had seven winters in zone 7 and five in zone 6, since 2000, saw two nights in zone 5 this year, with low temperatures of -15 and -14; another big variance.

The Polar Vortex 

So what exactly is the Polar Vortex?  Here is a good explanation from an NBC News piece from early January:

"The polar vortex is basically a great swirling pool of extremely cold air located tens of thousands of feet in the atmosphere.... Basically an arctic cyclone, it ordinarily spins counterclockwise around the north and south poles.  While it tends to dip over northeastern Canada, it's catching everyone's attention because it has moved southward over such a large population....Why has it traveled so far south? Chiefly, warmer air builds up over areas such as Greenland or Alaska and that air forces the colder, denser air southward.... "

And here is a statement that Paul Douglas prepared for this blog post:

" I remember some very cold winters in the mid and late 70s, but even then there was more variability in the jet stream, more fluctuations and mild periods in between arctic blasts. What is unique about this winter, in my opinion, is the persistence of this blocking pattern. We’ve gone nearly 3 months in a row with little variation in the jet stream over North America. This mirrors a larger (global) trend of slower jet stream winds over northern latitudes and more of a tendency for “blocking” patterns, where weather slows or even stalls for days or weeks at a time. Jennifer Francis at Rutgers has done some research on this “polar amplification”, theorizing that rapid warming of the Arctic and far northern latitudes is disrupting north-south temperature extremes, which, in turn, may be impacting jet stream winds, with more of a tendency for weather to become locked or “stuck”.

“ I've been tracking weather for over 40 years and I can’t remember a winter quite like this, the sheer persistence of the pattern to remain more or less stuck in place. Western drought, numbing cold east of the Rockies, with historic flooding for Britain and record warmth for much of Europe – it’s all interconnected. More research is required to confirm whether rapid warming in far northern latitudes (and summer ice melt in the Arctic) is, in fact, having a domino effect at our latitude, but with each passing year the weather is becoming more unusual, more extremes, more “weather-whiplash” (flood to drought, etc) and more volatility in general. I tell people the truth: we are changing the chemical composition of the atmosphere, conducting an experiment that’s never been done before. CO2 levels are at 400 ppm, higher than any time in the last 800,000 years. We’re poking at Earth’s climate system with a long, sharp stick and then acting surprised when the weather comes back to bite us.

Here are graphics that show the Polar Vortex incursion in the central U.S.  Note especially the warmer than normal zones in the Alaska and Greenland areas, which are responsible for pushing the jet stream and polar air southward:

The 64 trillion dollar question, so to speak, is whether this polar vortex incursion, caused by the unprecedented warming of the arctic regions, will reoccur in the years ahead.  There seems to be a fairly high probability that we will see it again but it seems to me that, as the earth continues to warm over the years, it may not be as extreme, i.e. the polar air will be warmer (not a good thing for the earth).  Consider again what Paul Douglas told us:

"... We are changing the chemical composition of the atmosphere, conducting an experiment that’s never been done before. CO2 levels are at 400 ppm, higher than any time in the last 800,000 years. We’re poking at Earth’s climate system with a long, sharp stick and then acting surprised when the weather comes back to bite us."

I am also a great believer in statistical trend lines, and the extreme minimum temperature (EMT) trend lines that I have plotted for almost all Midwest cities, for the years since 1962, show that we are all on a steady trend toward higher winter temperatures.  The Twin Cities' EMT trend line shows conclusively that we have moved into zone 5 and are on our way to zone 6 in just a few years.  One night of marginally zone 4 temperatures in 2014 certainly does not change the upward slope of our trend line in a meaningful way, so it is statistically reasonable to assume that we will continue to see warmer EMTs in the years ahead.

But, to use Paul's analogy, who knows what will happen when we poke the earth's climate system with a long, sharp stick?  My statistical prognostications for a warmer winter this year were certainly wrong and one of my good friends took the opportunity last week to give me a gentle push into a snow bank at Bredesen Park in Edina, as retribution.  Here is the Minnesota Rose Gardener making a snow angel in two feet of snow!

Finally, Twin Cities meteorologist, Jonathan Yuhas, (with tongue in cheek I'm sure) posted the following graphic on Facebook.  Notice any similarity to the polar vortex graphics above?  Oh well, smell the roses while we can; maybe sometime in July this year.

Jack Falker
March 5, 2014

Tuesday, February 4, 2014

Winter-Protecting Roses with Construction Blankets

This blog post is a joint effort between Deb Keiser, Rose Specialist at the Munsinger and Clemens Gardens in St. Cloud, Minnesota, and Jack Falker, “The Minnesota Rose Gardener”.

In the last few years a new method of winter-protecting roses has emerged in Minnesota, which we believe has application beyond the so-called “cold zones” of the Upper Midwest.   At the Virginia Clemens Rose Garden in St. Cloud (Zone 3/4), Rose Specialist Deb Keiser has stopped using the “Minnesota Tip” method and is now winter-protecting both her public and personal rose gardens with the insulated blankets cement contractors use in the winter to cure concrete in sub-freezing temperatures.  Construction blankets typically come in 6 X 25 or 12 X 25 foot sizes and have an insulating R-value of 7.5.  (We believe the R-value is important and blankets with less than an R 7.5 value may not be as effective.)

In earlier articles on preparing roses for winter: “Winter Protecting Your Roses”
( and “How Winter Affects Roses” (, I have advocated the following sound horticultural practices, in lieu of the labor-intensive Minnesota-tip method.
  • Plant the bud unions of hybrid tea roses 3-6 inches below the soil surface and the crowns of own-root roses at similar depths to protect from freezing and thawing. 
  • Give your roses a six-week potassium feast to harden off their canes for winter.
  • Use at least 3 inches of wood chips in your beds, year-round, and more around your roses in the fall.
  • Mound your roses with good compost in the fall, including lots of coffee grounds.
  • Tie up your roses in bundles and cut them back to about 8-12 inches, when they stop blooming.
  • Strategically place rodent bait containers around your roses to protect against vole damage.
  • Cover your roses with half-filled leaf bags or wire cylinders of leaves, when the ground first freezes or snow begins to accumulate, whichever comes first.  Hay can also be used for this purpose if it is packed closely around the mounded plants and held in place by bags or fencing.  Straw is less effective because it is less substantial and does not compost well.
  • Construction blankets are our other alternative, as we will discuss below.
The final steps above insure that your roses will not freeze and thaw repeatedly during the winter.  In the "warmer" cold zones, i.e., zones 6 and 7, insulating your roses, as described above, should have the effect of not allowing them to freeze in the first place; different than our expectation in zones 3, 4 and 5.

Enter Construction Blankets!

Deb and I agree on virtually all of the above steps, but she believes that using construction blankets, instead of leaves or hay, for the final protective cover in the fall is a better solution.  Seeing is believing, and I believe that Deb's practice, which she has been using for upwards of ten years now, has applicability not only in zones 3, 4 and 5, where the ground freezes solid every winter, but especially in zones 6 and 7 where constant freezing and thawing is endemic to most winters.

In late October, when the roses have stopped blooming (perhaps early November in Chicago or early December in zone 7), Deb mounds her roses and cuts them back, as mentioned in the bullet points above. If it is dry, you can continue to water the plants or, if you are still in the process of applying liquid potassium (which we highly recommend), that watering will suffice. Deb puts the blankets on her roses just before night-time temperatures go into the low 20s or snow starts to accumulate, whichever comes first.  This is all very similar to the practices cited in the bullet points above. 

For those of you not accustomed to cutting back your roses in the fall, please be assured that there is no downside in doing this, when they have finished blooming.  When roses are well mulched and protected all winter, they grow very aggressively in the spring, which is the strong growth you really want for the new season ahead (see the spring pictures of Deb's garden below).

Here is how the Virginia Clemens Rose Garden looks after Deb has cut everything back and begun covering with the construction blankets.  Note that she is careful to secure the blankets around the roses with lots of bricks.

And below is a picture of the Virginia Clemens Rose Garden fully covered.  Note that some of the trees still have a few leaves, so you can gauge the equivalent time where you live.  It starts to get cold in St. Cloud in mid-November, so Deb is striving to get everything covered, before the nights go into the low-twenties .  By the way, those Minnesota rosarians who still tip their roses are digging trenches and tipping their roses into them in mid to late October, which seems early to us, given that their roses have often not finished blooming, but that's how that process works.

And below is a picture of one of Deb's home rose gardens, taken in 2 degree weather on November 23, 2013. Note that 2 X 4s can be used to secure the blankets, as well as bricks.  All of this disappears, of course, once the snow covers everything.

And the Ground Doesn't Freeze!

Given the fact that the ground freezes several feet down in a typical Minnesota winter, regardless of snow cover, and that both mounded/leaf-covered roses and Minnesota-tipped roses are thereby frozen solid and simply protected from thawing and refreezing, I naturally assumed that the Virginia Clemens beds above would be similarly frozen and protected from thawing until spring.  I was, therefore, somewhat skeptical when Deb and her husband Dave Keiser told me in mid-January 2014, at the Twin Cities Rose Club meeting, that they believed neither the roses in the Clemens gardens nor the roses in their personal gardens were frozen under the construction blankets.  Keep in mind that the low temperature had already been -25 F in St. Cloud this winter and that there was more than a foot of snow on the gardens.

So, knowing that we were going to jointly write this article, Deb suggested that we should clear away the snow from the corner of one of the above beds and take a peek under the blanket.  That sounded like a fun way to play in the snow and, since the temperature was actually going to moderate for a day or two, I drove up to St. Cloud on January 24th and we initiated our little experiment with a couple of shovels and a commercial-grade thermometer to measure soil temperature under the blankets.  Here are pictures of the two of us "gardening" on that +30 F, late-January day:

 Here's Deb clearing away the snow from the edge of the covered bed.

Here's Jack reaching as far under the blanket as possible with the thermometer.  This is where we discovered that the ground was actually loose and friable under the blankets.  

We were actually able to stick the thermometer a couple of inches into the unfrozen ground and found it to be 33 and 34 degrees, in two separate measurements.

This is an impressive result, given that we were measuring a zone 3/4 garden in January, when the low temperature had been -25 F.  Interpolating this result to "warmer" cold zones such as 5, 6 and 7, it is easy to see how using construction blankets would be a relatively easy, sure-fire way of protecting sensitive rose gardens in any winter weather situation, perhaps especially in the warmer cold zones that experience constant freezing and thawing all winter.

Here are Deb's comments about what she is winter-protecting in both her personal and the Virginia Clemens gardens:  

"... At home I cover zone 6 & 7 grafted hybrid tea, floribunda, grandiflora, and shrub roses, a few own-root hybrid tea roses, miniature roses, zone 5 Flower Carpet shrub roses and David Austin English roses, Tess of the d'Urbervilles and Benjamin Britten.... At work I cover zone 6 and 7 grafted hybrid tea, floribunda, grandiflora and shrub roses, some own-root hybrid tea, floribunda and shrub roses, miniature roses, a bed of David Austin English roses, a bed of Buck roses and Knock Out roses...."

Deb further points out that all of her grafted roses are planted with their bud unions about 3 inches below ground level.  This is very important in any garden that experiences even the mildest of winters.  In our considered opinion, there is no justification for planting grafted roses with bud unions above ground level in any garden location.

Incidentally, Deb also puts potted miniature roses and tender perennials under the blankets in the Clemens garden.  If the pots are too large, the plants can be removed from their pots, laid on their sides, and mulched before covering with the blankets.  While Deb currently brings all of the garden's potted tree-rose "standards" into the garden's greenhouse, she believes that standards could be wintered under the blankets, as well, so long as the plants are laid on their sides and fully covered with mulch, before the blankets are applied.

And here's the proof of the pudding: pictures of Deb's gardens in early spring, when the blankets come off. Note that the roses have already started to grow under the blankets; ready to prune and take-off toward their first bloom cycle.  Once again, for those of you in the warmer cold zones, we do not believe there is any disadvantage in cutting your roses back and covering them thoroughly in the fall.  

Construction blankets are in common use by cement contractors in just about any area that experiences winter weather.  Apparently, most contractors rent their blankets, as required, and the best place to acquire them, either used or new, is likely to be rental companies that cater to those contractors.  Perhaps the best reason for this is that the blankets have to be stored someplace dry for more than six months of the year, which presents a potential storage problem for both contractors and gardeners alike. In Deb's case, she acquires most of her blankets in good, used condition from a rental firm in St. Cloud.  She also has the distinct advantage of having several, roomy, municipal buildings for storing her Virginia Clemens blankets in the summer time.  I might also mention that the Munsinger and Clemens Gardens, have a beautiful, large, new greenhouse, in which a large variety of roses and many other plants are profusely blooming all winter long. So who needs winter protection in Minnesota, when you have a climate-controlled greenhouse?  But that's another story altogether!

Both Deb and I would be happy to answer any questions you might have. 

You can reach Deb at;
and you can reach Jack at .

Deb Keiser and Jack Falker
February 4, 2014