How Windchill Affects Roses

Yesterday, we woke up in Minneapolis to a temperature of -17 F, with a windchill of -36 F . Every TV weather-person in town was wide-eyedly proclaiming the dangerous windchill temperatures, to the point, I'm sure, of scaring the average person, who had to go out of the house to work or school, half out of their wits. In fact, every school district cancelled school for the second time this winter, due to the windchill temperature.  Our most sophisticated local (and national) meteorologist, Paul Douglas, posed in his blog yesterday his rhetorical question of whether they cancel school for windchill temps in Canada?  It's no wonder people start believing that the temperature really is -36 in Minnesota, when -17 is quite bad enough.

Question: What temperature do you think our roses were "feeling" yesterday morning?

Simple Answer: -17 F.  Neither roses nor any other plant experience any temperature other than the actual ambient temperature.  And -17 is plenty cold, thank you very much.

Here's a good quote from a National Weather Service article about windchill:

"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)."

Here's that whole article

http://www.crh.noaa.gov/ddc/?n=windchill

Here's another good quote 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 here's that whole article:

http://www.ksre.ksu.edu/news/story/wind_chill121709.aspx

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.

Here's an example: Suppose that the ambient temperature is 35 F and the wind is blowing 30 MPH. According to the chart in the NWS article (above), 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.

Another example of the effect of wind chill on the human body is to go back to yesterday's -17/-36 situation.  If I go out for a walk, as I usually do in these temperatures, any exposed skin (like my nose) will be frostbitten in about five minutes because of the -36 wind chill.  That is a serious problem, especially for children waiting for school buses or people who have to work outdoors.  Children are notoriously bad at covering-up in cold weather and, thus, it is probably wise to cancel schools (in Canada too).  And, while my plants certainly are not feeling the wind chill, the old Minnesota Rose Gardener certainly is, so he has to dress accordingly in his thinsulate-lined parka and antarctic mask.

The temperature was about -2 and the wind-chill about -15 when this picture was taken.

Cold enough for ya?  It sure was for me!

So, bundle up and make sure your roses get the right winter-protection each winter.  See my blogs "Winter Protecting Your Roses":

http://theminnesotarosegardener.blogspot.com/2013/09/winter-protecting-your-roses.html

and "How Winter Affects Roses":

http://theminnesotarosegardener.blogspot.com/2013/12/how-winter-affects-roses.html


Jack Falker
January 24, 2014

Deb Keiser's Reflections on the 2013 Growing Season

The following  is a guest post from Deb Keiser, Rose Specialist at the Virginia Clemens Garden in St. Cloud, Minnesota.  Deb is a Twin Cities Rose Club member and, in my opinion, one of the most knowledgeable rosarians in the country.

In my last "Minnesota Rose Gardener" blog, "How Winter Affects Roses", I described an unusual situation that occurred in 2013:

"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.... 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?"

Here is Deb's description of what happened in the Clemens garden in 2013, including the loss of 12% of their roses, which is highly unusual for a professionally run garden that uses state-of-the-art winter protection methods. It is eerily similar to what many, if not most, Minnesota rosarians experienced in 2013.

Mid December Reflections on the 2013 Growing Season

By Deb Keiser, Clemens Garden’s Rose Specialist

The weather in April and May 2013 will be remembered as “extreme” and “record-setting” in many parts of the United States. St. Cloud, MN was no exception to this. We broke several long-standing records and experienced extreme weather fluctuations.

To plan for the date that our garden staff will uncover the construction blanket covered roses at Clemens Gardens, I often start watching the forecast high and low temperatures near the beginning of April, with a target date of the week of April 15^th as the estimated time for the actual uncovering. With widely fluctuating weather this past April, Mother Nature kept us anxiously waiting and watching for warm weather for quite awhile. On April 11, 2013, St Cloud received 8.7 inches of snow. The high temperature on April 15, 2013 was 36 degrees. We had freezing temperatures every night that week. On April 18, 2013, we received another 9.4 inches of snow and we set a new record for most snowfall in April with a total of 24.4 inches for the month. On April 20, 2013 we set a new record with a low temperature of 16 degrees in St. Cloud.  I knew it would take awhile for the snow to melt with temperatures like that, so I set my new target date for May 1, 2013. Then on April 27^th, we had a high temperature of 74 degrees with a low that day of 30 degrees. Crazy weather indeed! April 28^th brought us a 77 degree day followed by a couple of days in the low 70’s which made uncovering the roses seem very tempting, except for the 10 day forecast. Just when we thought it was finally safe to uncover the roses, an early May snowstorm dropped a record-setting 18 inches of snow on parts of southeastern Minnesota. In St Cloud, we were fortunate not to get snow but we did have high temperatures in the low 40’s, a low of 28 degrees, and ¼ inch of rain from May 1^st thru 4^th. With a rose pruning day for volunteers scheduled for the evening of May 6^th, a high temperature of 72 degrees that day and 70 degree temps forecast for the week, I decided that we could finally uncover the roses. As luck would have it we experienced freezing low temperatures the following weekend, followed by a high of 95 degrees two days later. Only in Minnesota! If you don’t like the weather, just wait awhile and it will change!

Here is a re-cap of the 2013 rose growing season at Clemens Gardens, highlighting some of our achievements and some of our misfortunes.

Misfortunes –

When uncovered, the tender roses in the Virginia Clemens Rose Garden looked alive but not leafed out as in past years. This was probably due to the late cold temperatures in April and May, prior to uncovering them. This made for a late first flush – July 4^th weekend, as compared to a Memorial Day weekend first flush in 2010, a June 20^th first flush in 2011, and a mid-May first flush in 2012.

Our pruning season started late, our weather warmed up fast, and it was off to the races to try to get over 1,800 roses pruned before they were totally leafed out. With only one assistant and a handful of volunteers, we were still pruning roses in mid-summer.

We lost 140 hybrid tea and floribunda roses in our 1,200 rose Virginia Clemens Rose Garden, or about 12%. Fortunately, most of the roses were older roses that were in the gardens prior to when I started working here in 2004, and some were donated packaged roses from 2006 and 2007. The roses were probably weak to begin with from the 31 days of 90 plus degree heat and drought conditions in July 2012. The late cold weather after uncovering them did not help either.

Due to the late start to the season our Bob’s Mix fertilizer was applied much later than normal. The weather at application was hotter and drier then usual. We did not see a big growth spurt in the roses until we had rain and cooler temperatures late in the season. The roses were much shorter than normal and did not produce as many blooms.

Our Award of Excellence (AOE) miniature rose trials entries for 2013 arrived the week of April 25, 2013 and had to be repotted and grown in the Munsinger & Clemens Gardens’ greenhouse until it was warm enough to plant them outdoors. They were moved out to the AOE trial garden later than normal, which meant less time for the AOE Evaluators to evaluate them.

Achievements –

The long cold spring gave our 95 new roses from Weeks Roses, our five shrub roses purchased from Twin Cities Rose Club’s fundraiser, and our sixteen 2013 AOE trial miniature rose entries plenty of growing time in pots in our 10,000 sq ft greenhouse.

We received plenty of moisture early in the 2013 season to get the uncovered roses and hardy shrub roses started growing well in the garden beds.

The shrub and Old Garden roses that we moved from UMORE garden in October 2012 and planted in our lower rose garden, came through the winter very well with only compost for winter cover. I was pleasantly surprised at the winter hardiness of the zone 4b & 5 roses – four ‘Double Knock Out’, seven ‘Carefree Marvel’, and two ‘Salmon Impressionist’. All of the shrub roses from UMORE grew and bloomed well during 2013. The ten plants of ‘Winnipeg Parks’ which were planted on the rock walls bordering the front and south side of the Virginia Clemens Rose Garden were constant bloom producers. I heard many visitors commenting on their beautiful large pink flowers. The OGR divisions off of the UMORE “mother” plants experienced nice growth and may bloom for the first time in June 2014. I look forward to seeing all of the spinosissima, gallica, alba, & moss roses in bloom.

The shrub roses in our Lower Trial Rose Garden proved their winter hardiness by surviving the winter with only a 4 inch layer of rice hull mulch and snow cover for winter insulation. These include ‘Pink Home Run’, ‘Carefree Sunshine’, ‘Peppermint Pop’, Northern Accent roses ‘Ole’, ‘Lena’, ‘Sven’, and ‘Sigrid’, Easy Elegance roses ‘Little Mischief’ and ‘Sunrise Sunset’, ‘Carefree Wonder’, ‘Como Park’, ‘Thrive!’, ‘The Charleton’, and Kathy Zuzek’s trial roses. Blackspot was not a problem in the Lower Trial Garden, even though the rice hull mulch had been wintered over from the previous season. The shrub roses were very disease free this season.

  

We replaced most of the soaker hoses in the Virginia Clemens and Upper Trial Rose Gardens with new ¾ “ Osmile double-thick wall soaker hoses with a lifetime guarantee. The hoses were put in place prior to the hot, dry weather in July and August. They worked very well during the season with much better water output than the older hoses. The best thing was no more fixing broken soaker hoses. We will replace the rest of our soaker hoses next summer.

Although it was later than normal when we planted our new potted roses from Weeks, Twin Cities Rose Club, and AOE entries outdoors, they transplanted and grew well. Many of the plants were already in bloom and were good sized plants when planted outdoors. I was especially impressed with the three test roses that Weeks sent us. All three plants grew well and their blooms quickly became noticed by visitors. The large golden orange long-stemmed blooms of hybrid tea rose ‘Good As Gold’ and the large fragrant bright yellow old-fashioned blossoms of grandiflora rose ‘Happy Go Lucky’ seemed to put on a constant display. Both were very disease resistant. Although grandiflora rose ‘Coretta Scott King’ with its beautiful long coral and white buds and disease resistant foliage did not bloom as much as the other two test roses, its big clusters of blooms were very long lasting.

In early July, we purchased 16 very nice large potted hybrid tea and floribunda roses from Linder’s Greenhouse during a 50% off sale and 24 own-root hybrid tea and floribunda roses on sale from Roses Unlimited. They performed well and added many older varieties that are new to our gardens. The three plants of floribunda ‘Oh My!’ with its dark velvet red blooms and the bright red blooms of hybrid tea roses ‘Olympiad’ and ‘In the Mood’ from Linders Greenhouse put on a good display along the Upper Trial Garden walkway through the Clemens Rest Area Garden. The two pink bloomed ‘Sexy Rexy’ floribunda roses and the two ‘Estelle’ hybrid tea roses with their florist quality russet blooms reversing to yellow drew many comments from visitors to the Virginia Clemens Rose Garden. Both were purchased from Linders. We were sad to hear of the closing of Linder’s Greenhouse. They were a generous donor of many good quality roses to our gardens and a good source of quality plants and shrubs for Minnesota gardeners. They will be missed!

We only had one week of 90 plus degree weather in mid July and another week of  90’s at the end of August. Unfortunately, it was during the MN State Fair. Most of our July, August, and September temperatures were in the mid 70’s to low 80’s, which made for wonderful working conditions at the gardens. Our rainfall was below normal but the new soaker hoses worked well. We fertilized the roses with Alaska Morbloom fertilizer 0-10-10 after August 31^st and the roses continued to bloom and grow.

In September and early October, we gave the Virginia Clemens and Upper Trial Garden roses doses of potassium sulfate 0-0-50 to help ready them for winter. I chose potassium sulfate with the hopes of lowering our soil PH from almost 8. We also treated areas of the Virginia Clemens Rose Garden, where our roses were experiencing growth problems, with fast-acting sulfur (calcium sulfate) also with the intent to lower the PH in those areas to improve growth for 2014. I will be checking our soil PH again next spring and adding amendments as necessary to correct our PH.

Winter came early with cooler than normal temperatures in mid October, so we started our winter protection process of cutting back the tender roses to 8 inches of height. This allows us to cover the rose beds tightly with insulated construction blankets. We mulched the roses with two large scoops of finished compost over the crown and extending out to the sides of the rose plant.  With temperatures threatening to drop into the teens at night, we applied insulated construction blankets to the rose beds in the Virginia Clemens and Upper Trial Rose Gardens on November 7^th and tucked our roses in for their long winter’s nap a few days earlier than in past years. So far this winter, we have had a good amount of snowfall to add additional cover to the rose beds.

Now we plan for next season with the hope of an earlier start in the spring with less winter damage, followed by adequate rainfall and warm sunny days for good growth, and an insect and disease free season. One can only hope that Mother Nature is good to Minnesota gardeners next year!

As always, let Deb and me know what you think.

How Winter Affects Roses

This is a revision of my 12/27/2013 post, based on several good comments I have received from Dr. Gary Ritchie and a number of other readers.  Thanks for the enthusiastic responses from so many rosarians, whom I hold in high esteem.
 JRF 12/29/2013

At the peak of winter here in the cold zones, our roses are "winter protected" to help them survive the sub-zero temperatures of USDA zones 4, 5, and 6.  Most folks look out at their roses covered (hopefully) with a nice layer of snow and believe their roses are dormant; just waiting to thaw out, break dormancy and start growing again.  But wait....  Did you know that only species roses, such as Rosa Rugosa, Rosa Glauca, Rosa Gallica etc. go through a dormancy cycle and that all modern, repeat-blooming, "remontant" roses do not?  So what's going on here with modern roses in winter?

Before I try to answer that question, I want to say that I recently learned much of this from "Dormancy in Roses", an excellent four-part series in the American Rose, during 2013 and early 2014, by Dr. Gary Ritchie of Olympia, Washington (see footnote below).  I will quote Gary several times in this post and want to give him full credit for his research and opinions.  However, I also want to note that Gary's articles have raised some important issues for me, based on my many years of successfully growing modern roses in Minnesota; in particular, why keeping modern roses frozen hard in the winter is what keeps them alive, rather than killing them outright. This seems somewhat contrary to the conclusion of Part 4 of Gary's article, where he says:

"I've not seen data on specific cold hardiness of modern roses but experience indicates that it is modest at best. So, while we enjoy continuous bloom throughout the summer, we face the annual chore of winter protecting our roses.  Here in the moderate coastal Northwest, this requires no more than mounding up our plants in fall.  But in more extreme climates winter protection can be much more difficult and problematic -- sometimes even requiring burying the plants underground to assure their over-winter survival." 

Here is how I would re-phrase Gary’s quote (above) from my perspective in zone 4/5:

"I've not seen data on specific cold hardiness of modern roses, but experience indicates that, with good winter protection, most modern roses, including budded hybrid-teas, are very cold-hardy, as long as they are allowed to freeze solid and stay frozen all winter.  Here in Minnesota (zones 3, 4, and 5), winter protection begins with planting bud unions four to six inches deep, mounding with dirt or compost in the fall, and subsequently winter-protecting with leaves or hay after the ground freezes in late fall or early winter. Another alternative is the Minnesota Tip method of burying plants underground.  Both methods have as their objective keeping roses frozen throughout the winter; not to keep them from freezing, which is virtually impossible in our zone 4/5 winters."  (JRF Quote)

In other words, the whole purpose of winter-protecting roses in the cold zones, where the ground freezes from several inches to more than a foot down, is to keep roses from repeatedly freezing and thawing. The only exception to this might be the use of insulated R7.5 construction blankets, which are gaining popularity in Minnesota.  My friend and TCRC mainstay, Deb Keiser, who manages the Virginia Clemens Rose Garden in St. Cloud, believes that putting construction blankets down before the ground freezes keeps her roses from freezing in the first place (which is quite an achievement in St. Cloud!). But the principle is the same, whether the ground freezes under the blankets or not:  i.e., to keep your roses from repeatedly freezing and thawing.  This can be problematic here in the Twin Cities (now in zone 5) and even more so in zones 6 and 7, where mid-winter thaws are more frequent.  Take a look at my recent article on winter protection:

http://jack-rosarian.blogspot.com/2013/09/winter-protecting-your-roses.html


Here is how two of my rose beds looked on Christmas Day 2013:

Buck Earth Songs under a foot of snow insulation

Terraced Canadians and Bucks

Now, just in case I have given the impression that I'm not growing hybrid teas in Minnesota winters, here is my winter-protected Elina on a -2 F. afternoon in Edina.  The reason the leaf bag is showing under the snow is that we had a record-breaking 48 F. the day before I took this picture; a 50 degree swing!  And that's what winter protection is all about in zone 4/5: to keep the roses from thawing and re-freezing in these crazy temperature swings!

Above: Elina in a Minnesota Winter

Dr. Gary Ritchie's point about modern roses not going into dormancy is obviously correct. Unlike woody perennials like Rhododendron or lilacs, roses apparently do not have a dormancy "chilling requirement"  in order to generate next season's bloom cycle. Rather, as Gary says, modern roses, as remontant, repeat-blooming  plants, "by their very nature, fail to go dormant in winter. So they have a much-reduced ability to cold harden."  In other words, rose canes die back in winter because they do not sufficiently "cold harden" and this die-back can only be controlled at the crown or bud union levels by proper winter-protection, as described above.  This affirms something that I have advocated for many years, i.e., repeated applications of potassium in the fall to "cold-harden" rose canes before the first hard freeze. My experience, over more than 20 years, is that hardening rose canes off with a potassium feast has the effect of significantly reducing cane die back in the winter.  Please see my several articles about the "potassium feast":
http://jack-rosarian.blogspot.com/2012/08/potassium-special-k-ration-feast-for.html

http://jack-rosarian.blogspot.com/2013/10/rose-potassium-feast-application-6.html


But something else seems to be happening here

Over the last several years, as the Twin Cities metro has moved solidly into zone 5, my observations indicate that modern roses may exhibit a characteristic, which may be related to the chilling requirement inherent in plants that experience dormancy in winter.

Even though our winters are warmer, in terms of extreme minimum temperatures (EMT), they seem to be just as long, or perhaps even longer in certain years, thereby keeping our roses frozen for a longer period of time. For example, our ground (and therefore our roses) stayed frozen into late April or early May in 2013, and we had snow on the ground into early May.  This is 2-4 weeks later than normal. What happened in May, once the ground thawed out, was that the roses had a very hard time getting started and there seemed to be more die-back than usual, even with shrubs that are zone 3 and 4 hardy. One of our husband-wife TCRC members,who have had good success over the years planting their hybrid tea and shrub roses with bud-unions and root crowns six inches below ground level, and using minimal winter protection above ground, lost a number of roses in 2013, even though the same method had worked perfectly in colder EMT winters.

In other words, with a 2013 EMT of -13 (well above the median for zone 5), our roses actually seemed like they had been through a much harder winter.  So it would appear that the length of time roses are frozen, not just the low temperature in a given year, impacts survivability.  After all, if you think about it, frozen is frozen; the only thing that happens with a lower temperature is that the ground freezes deeper and the roses take longer to thaw out and start growing in the new season.  But what happens to them when the winter is so long that they can't start growing again in a timely way?  To my knowledge there is no scientific reasoning for this phenomenon.  However, I found a clue in Part III of Gary Ritchie's series, where he speaks of cold weather breaking dormancy in plants.  Speaking of dormant plants in the first person, he says:

 "...One way would be somehow to keep track of the amount of cold weather to which you had been exposed during winter.  After a certain number of hours or days of cold exposure had occurred you would have a clear indication that winter was finally over and it was safe to resume growth.  This is exactly what plants do...."

What he is saying is that dormant plants apparently have an internal clock mechanism buried deep in their DNA that tells them it's time to start growing again, after they have been exposed to a certain number of hours or days of cold weather.  However, what happens if that internal clock tells them it's time to grow and they're still frozen solid?

Now, this is pure conjecture on my part but, based on my observations in the past year, I would theorize that (1) modern roses, although they do not experience dormancy, might share a similar DNA clock mechanism with plants that do, such as their first-cousins, the species roses; and (2) the growth signal coming from within the plant might be distorted by longer than historically normal periods of remaining frozen, such that the plant's internal growth pattern is interrupted, or even curtailed altogether, thereby causing much slower growth or even plant death.  This could account for what I and a number of Minnesota friends experienced in our warmer, but longer than normal, winter of 2013.  This was truly something I had never seen in my near-lifetime of growing roses in zones 4, 5 and 6.

I 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
jack@falkerinvestments.com
December 27, 2013

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!

Rose Potassium Feast: Application #6

I put down the sixth and final liquid potassium application on my roses yesterday, getting them ready for winter.  In case you haven't been following my blog posts on this subject, here is a synopsis:

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 recent article on winter protecting your roses:  http://jack-rosarian.blogspot.com/2013/09/winter-protecting-your-roses.html

Here is a quote from Burpee’s American Gardening Series book Roses, by Suzanne Frutig Bales:

“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.” 

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 begin my roses’ potassium feast in the second or third week of September.  That takes me through the end of October or beginning of November, which is about as late as I want to go.  There have been years, perhaps when I started a little too late, that I’ve had to thaw out my hose or turn off my water and turn it back on again in order to complete the sixth treatment.  My advice is don’t wait too long, because it’s better to be too early than too late with this. 

Here are a few pictures of yesterday's application, taken by Mary Eileen (a.k.a "The Head Deadheader"):

Each rose gets one gallon of the mixture for six consecutive weeks.  It has the added advantage of hydrating the plants weekly as we head into winter.  Note that it was a very nice day yesterday; a lot nicer than it has been for many of my sixth applications.

I mix the potassium in 34 and 64 gallon trash containers and pump it out with an inexpensive sump pump, through a hose and watering wand (you can see the pump's electrical cord going into the container). This little trick of using a sump-pump for applying liquid fertilizers is a huge work-saver throughout the growing season. Muriate of Potash is a reddish, crystalline substance that doesn't dissolve as easy as most liquid fertilizers.  I use as much water pressure as I can muster, through a nozzle turned on all the way, to get it dissolved.  The sump-pump goes in after the tank is full.  Note how the potassium has red-stained the trash container in the picture below.  It will do that to your clothes too, but it washes out (eventually)  :)

Here I am with the 64 gallon container working on four of my Buck Earth Song plants.

I get Muriate of Potash (0-0-62) in 50-pound bags at Waconia Farm Supply, which is exactly 10 miles past the Minnesota Landscape Arboretum in Waconia.  A 50-pound bag of Muriate of Potash costs about $25 and lasts me five years or more.  For those of you outside of Minnesota, you will need to find a real farm supply store because it's pretty unlikely that you will find Muriate of Potash at your local nursery. 

  

After about the third-week’s application, you will begin to notice that the canes of your roses are turning a pretty shade of deep red, so you can actually see them hardening-off for the winter, which is fun to watch. 

 I believe that this method of winter protection is particularly interesting for northern gardeners, as we see the continuing effects of climate change in the rose garden. While putting on liquid-potassium for six weeks seems to be a lot of extra work, I think it can ultimately reduce the overall work of winter protection, once you gain confidence using it in your own garden. 

Here are two of my articles on the "potassium feast" from last year, as well as my recent article about winter protecting your roses:

http://jack-rosarian.blogspot.com/2012/08/potassium-special-k-ration-feast-for.html

http://jack-rosarian.blogspot.com/2012/10/potassium-follow-up.html

http://jack-rosarian.blogspot.com/2013/09/winter-protecting-your-roses.html

Vole Defense!

Considering a turn on an old saying, that a good defense begins with a good offense, I thought everyone would like to see our offensive effort to defend against voles this fall.  His name is Crackie, he's a six-year old Maine Coon and, needless to say, he's a mouser.

Voles are feisty; as Crackie toyed with it, it fought back aggressively but the cat flipped it upside down and then I went to get my shovel to finish it off.  Crackie didn't like me taking away his new play thing, so I had to give him some treats.

In case you missed it, here's my most recent post on vole control in the rose garden. It also

contains two other links to vole articles I wrote last year.

http://theminnesotarosegardener.blogspot.com/2013/09/voles-and-castor-oil.html

One of the things I mention is that, because cats go after voles, you should be very careful to use the right kind of mouse bait to kill them.  Here's a quote from my original article: 

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 to save this humane society kitty and, fortunately, he is still with us (but he used two or three of his nine lives on that one).

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.  There is no question that it would kill any animal if eaten in sufficient quantity, but it apparently is less dangerous because it kills the rodent and dissipates rather than staying in the animal as the anti-coagulant does, thus potentially transferring to another animal or predatory bird (owl or hawk) that might eat the dead or dying rodent, as we believe our kitten did.  Note that Motomco also makes a similar product labeled as mole bait that uses Zinc Phosphide, so if you can't find Eraze, you can use the mole bait (check the label to be sure).  Other companies also offer Zinc Phosphide under different brand names.

My first line of defense in controlling voles is castor oil (and Crackie).  My second line of defense is  zinc phosphide baits in small tin cans, carefully placed around the roses after my winter protection goes on the beds.  I'm pretty sure that Crackie can't get at the cans and that, if he does bite into a dead vole, he's not likely to die from residual Zinc Phosphide in the animal.

And we don't want to hurt Crackie.  He's a good kid!

Starbucks Coffee Grounds for your Roses

Starbucks doesn't like to throw their grounds in the trash, knowing that gardeners can use them organically.  At one time, they even had special bags labelled "Grounds for your Garden".  So don't be shy about going into your local Starbucks and asking for grounds.

I've said a lot about the benefits of using coffee grounds on your roses.  Here are my postings on the subject:

http://jack-rosarian.blogspot.com/2013/03/coffee-grounds-and-roses.html

http://jack-rosarian.blogspot.com/2013/05/gettin-wormy.html

Last Sunday morning, after finishing our coffee and reading the paper, Mary Eileen, my chief deadheader and best buddy of nearly 50 years, took my picture coming out of Starbucks with a 30 pound bag of grounds, destined for the compost pile that will be mounded around the roses  in preparation for winter, in a few weeks.

Here's how the bag looked when opened up.  A lot of expensive lattes went into that brown gold.

And here's how my compost  pile looks with all the grounds worked in.  It's amazing to see how many worms surface when you turn over the pile.  All of this will be going on the roses in a few weeks, when we do our winter protection.  That's Butternut and Zucchini squash at the back of the pile.  It flourishes there, as well. Yum!

Voles and Castor Oil

I was delighted to see Ted Mills' "Rose Doc" article "Voluminous Voles" in the September/October 2013 issue of American Rose.  Ted's articles are always great and are just one of the many benefits of belonging to the American Rose Society.

Ted does an excellent job of describing voles and why they are such a pain for all rosarians, especially those of us in the north who winter protect our beds and thereby inadvertently create winter habitats with unlimited tender food for these ravenous little creatures.  If you've ever had an entire rose bed destroyed by voles totally girdling the canes of every rose, right at ground level, you know exactly what I mean.

Ted gives some good suggestions and warnings about using rodent poison and mentions a product that I hadn't heard about and an am going to look for: Shake Away Rodent Repellent, but he apparently hasn't heard about the best repellent of all:  Castor Oil!

I published an article "Voles!" in October 2012, which mentions many of the same things Ted does and also provides some pictures in living color of these nasty little critters.  I also provided everything you need to know about using castor oil as a vole repellent, as well as a very good video on the subject from a New Hampshire hosta nurseryman.  Here is my article:
http://theminnesotarosegardener.blogspot.com/2012/10/voles-and-roses.html

I also published a follow-on article: "More About Voles and Castor Oil" in November 2012. And here is that article:
http://theminnesotarosegardener.blogspot.com/2012/11/more-about-voles-and-castor-oil.html

I have been using castor oil, mixed with soap and water, on my beds for the last few years, and I believe I can now say with certainty that it does repel voles.  Just be sure to use it liberally in all of your beds and the voles will go elsewhere. Remember, however, that "elsewhere" might be somewhere else in your garden; in my case last year they chewed almost all the way around the trunk of a new flowering crab tree, within about 30 feet of one of my rose beds.  Needless to say, I will be putting the castor oil mixture around a few other tasty plants this fall.

As always, feel free to comment below or send me an e-mail:  jack@falkerinvestments.com


Jack Falker
September 17, 2013