CO-Horts Blog

Thursday, November 13, 2014

Aw Snap! (Cold snap, that is.)

Posted by: Alison O’Connor, Larimer County Extension

As weather forecasters were predicting our cold snap that we’re currently suffering through, I began thinking about our outdoor plants and wondering if they had hardened off. Others thought the same thing, because a recent listserv had chatter of comparing this cold snap to the Halloween Freeze of 1991. In short, the spring of 1992 proved to be fatal to many trees and shrubs, particularly Siberian elms. 
Nerd alert! Taking photos of plants in sub-zero weather.
I don’t have any elms in my landscape, but I do have many roses. And my curiosity was spurred this week by a woman who emailed asking what she could do to protect her roses. After all, ours were both still blooming and the leaves hadn’t dropped. It seems all of these things (below-normal temperatures, tender green tissue and blossoms) are pointing to one thing—likely major dieback and possibly plant death come spring 2015.

Boy howdy. That stinks. I love my roses.

I consulted with Larimer County Master Gardener and Rose Guru, Roger Heins, on his take on the subject. He expressed similar sentiments, unless people did some extra preparation (he did). I did not. But here are his recommendations for future consideration:

  1. Two or three days before the cold weather sets in (and when daytime temperatures are above freezing), deep water your roses. Actually, take the time to water all of your trees and shrubs.
  2. After the first two initial temperatures of nighttime temperatures below 30 degrees F, but before a hard freeze (<26 degrees F), pull bark chip mulch (or soil) around the base of the roses. If there is still foliage, don’t make the bark mulch too heavy…wait until leaf drop.
  3. If you have roses with long canes (one of my “shrub” roses is over 8’ tall), you can prune the canes back by 1/3 to reduce injury from snow, ice and wind.
  4. If you have blooms on the plant, remove these, as they can collect snow and ice and cause the canes to bend or break.
  5. After the roses go dormant and lose their leaves, increase the mulch depth around the base of the plants. The rule of thumb is to mulch about 6-8” up the canes. As the roses come out of dormancy in spring, remove the mulch.
  6. If you have the time and ability, you can wrap the roses in burlap.
Roses in bloom on 11/12/14.
Remember, snow isn’t a bad thing—and can act like an insulator.  But we generally can’t rely on continuous snow cover through the winter, so extra precaution is a good thing. Because my roses are an important part of my landscape, I will mulch them once I can stand to be outdoors for longer than 30 seconds. And I’ll put it on my schedule to water them once we get those glorious warm winter days. 
Snow can be a great insulator for roses.

Until then, I’ll be anxiously awaiting the arrival of spring to see how this polar vortex affects our landscapes. And keeping my fingers crossed (inside my mittens).
Not a rose! But the red arils on burning bush are beautiful.

1 comment:

  1. Hi from the Roger quoted in Alison's Blog. I wanted to explain a little further on my pruning suggestions in her post. The forecast called for sub zero temps with wind, ice and snow in my hill top Windsor area. Some of my roses had very long canes. So long they were hanging over into the yard, but because they were still producing awesome blooms I had left them alone. With ice and snow coming I was concerned that those long canes would get weighed down to the point that the canes would break at their base. Not good for the bush, so I trimed a little over a 1/3rd of only the real long canes back. Same was true of my English roses that still had large heavy flowers on the end of tall canes. I deadheaded the rose bloom off those English beauties two inches below the bloom. Just know that it is usually best not to prune roses until they go completely dormant. Even then I will only prune them by 1/3rd. I leave most flowers on and allow the rose hips to come forth with a unique winter show.