Back to the drawing board

This past winter was devastating to roses grown in more exposed locations in the Edmonton, Alberta area. Many shrub roses, including Rugosas normally cold hardy to Zone 3 located at the Devonian Botanic Garden, were almost nailed to the ground. I also noted more winter kill to Explorer Rosa kordesii and Parkland roses in the city. I’m assuming that was likely the case in general on the Canadian Prairies. Ironically, it seemed to be just an average winter. Perhaps even warmer than usual. Initially, I thought the dry late summer and fall was the main factor causing this. But, for example, the St. Albert Botanic Park rose garden just north of Edmonton was well irrigated during this time. So maybe that wasn’t a factor.

As a result of this situation, I’ve had to re-think some of my breeding programs. Since I work a lot with Rugosas, the first thing will be to inject more very cold hardy species into them. Example, Rosa acicularis, which has been badly neglected for developing cold hardy (Zone 2 - 3) roses. Secondly, in my program of developing crown hardy roses to Zone 3, using the Rosa kordesii L83 breeding germplasm much more. It’s important that when crown hardy roses to Zone 3 are winter killed to the ground, the plant will begin to grow vigorously again in the spring. I am thinking that if L83 is combined with relatively cold hardy (Zone 4) cultivars or breeding lines this should happen. Of course, one should also take advantage of existing cultivars with L83 in the parentage or pedigree. George Vancouver, for example.

I had some erratic response to this winter, but generally following suite for the truly hardy in my garden that damage was minimal … odd ones are a double blush Burnett that is about 6 to 8 years old. Just tonight I was noting 1/3 of the canes (highest ones) no leaves and showing the distinct light brown patches of through cane damage , 1/3 leafing out and last 1/3 well formed buds already - never can remember seeing such odd behavior.But I must confess that for some reason my “short” rugosas are lost … don’t know why … the dagmars such as red dagmar gone to my eyes.

Yet 4 feet away Williams Double Yellow fully leafed out. Northern Encore lost 1/2 it’s size evenly all around but slowly leafing out from the centre - damaged canes turn black. Queen Mary of the Scots usually has some damage but not this year … full leafing out. R. primula is just perfect and White Star of Finland looks to only have lost a few canes. All explorers lost 1/2 to all canes. Mordens 1/2.

Soleil d’ Or maybe lost 5 inches on a three foot cane. … but his one looks like hel lbecause blackspot has weakened it from what it looked like in year two … the one refer to is about 6 years old … another couple in the north gardens may lost 6 inches.

However marginals and tenders were obliterated to the ground in the majority of the cases even where covered. But as I said And now for the truly odd, quite a few of my newer austins in the north gardens have at least "40% good cane and leafing out like mad … nothing is consistent except generalizations that tenders will be dmaged sevrely.

Surprises were my near species gallicas such as Agatha/e Rosa Mundi, and I forget the name of oldest one at the moment “apothacary” I believe is an alternative name … all canes survived and starting out at two to three feet.

I also lost a Brandon elm (6inch caliper trunk) and an Amur Cherry - bloody odd.

On weather, the big difference is the cold weather came here in early December and stayed cold for the most part with lots of snow … thought the results would of been better than I am seeing. I am pretty sure this year I soaked in the fall.

I was just thinking that other day that I had more winter damage than usual. I’ve lost some roses that were at least 3 years old and had been mulched as usual. The canes of William Baffin and John Cabot that were above the fence are dead. One of my holly bushes was severely damaged and several sunburst locust trees on the street are really struggling.

I’m not sure what the difference in weather is, other than to say that it has been a very cold, wet spring.


Have you considered working with ‘Will Alderman’ instead of R. acicularis directly? ‘Will Alderman’ is a very sturdy shrub and proven fertile, although I am unsure of its ploidy. Henry Kuska has used it a lot in his work, with success. I have an F2 ‘Will Alderman’ seedling I am using these days in my own work, although I am in no position to determine cold hardiness limits here, unfortunately.

Definitely continue pursuing L83, as Svejda stated that both extreme cold hardiness and disease resistance was coming out of that plant.

I have made a cross this year of “Will Alderman F2” X L83, and the reciprocal. Although L83 is difficult to get seeds from, it does happen occasionally. This year I was surprised to find that I got one seedling from L83 X ‘Home Run’ which seems to be doing very well so far. I find a percentage of ‘Home Run’ seedlings die a few weeks after germination.

Here in the front range of Colorado a big factor that figures into cold hardiness is water. Since we get such little precipitation beginning in summer and ending in late winter many plants die off because of the added affects of cold and dehydration. Plus we have very little snow coverage to go with that. So the same thing could have happen to you if you fall was extra dry.

I have a cane hardy lax seedling from Belle de Crecy x Flower Carpet Red. Last spring I noticed that one of it’s op seedlings had the fuzzy stems of it’s nearby neighbour, a seedling of Henry Kuska’s Hsnsa/acicularis op. Somehow I neglected to plant it, but it survived our very cold winter in a pot, & is now thriving. There are no buds this year, so the flower is still a mystery. But this is some indication that such crosses could easily work with hardier roses of OGR parentage.

Also in my garden is a seedling from a rose termed “pycnacantha” by David Zlesak who provided the seeds. A good number of op seedlings from White Nights x Chianti have the characteristic thick lime coloured foliage & plant habit of “pycnacantha.” These roses were also left out in pots with no cane damage. One of them should bloom in a couple of weeks. Chianti itself is not cane hardy in my garden.

Its interesting to note that Williams Double Yellow was mentioned as having no damage where others were showing lots of cane damage.

A while back, someone from one of the scandinavian countries stated that Williams Double Yellow was more hardy than Hazeldean which died back consistantly.

Paul O had found it very interesting because Hazeldean was very hardy for him. Its an interesting correlation that during a winter when many hardy roses had damage where Williams Double Yellow did not.

I am using its pollen in as much as I can so it will be interesting to see what is the result from it.

In answer to Paul Barden’s question about the chromosome count of Will Alderman. A microscope picture of its pollen is at:

It appears to be a diploid.

Thank you Henry. I’ve started using pollen from an F2 ‘Will Alderman’ hybrid on various roses and I had been assuming it was either tetraploid or maybe triploid, considering that R. acicularis is listed as a hexaploid in most instances. I’ll be using it a bit differently now if its a diploid. Thanks for that info.


I had a small plant of Hazeldean which was planted last year. It was growing quite vigorously. Although I am currently watching it at the base, it appears to be dead. My William’s Double Yellow was a bigger plant (also new last year) and it survived the winter with selective damage–some canes will need to be removed completely and some are viable right to the tips. I also found this type of damage typical of Harison’s Yellow until I removed it because of terrible blackspot susceptibility. All other Spinosissima roses were tip hardy.

I considered the past winter to be fairly normal for northern Wisconsin. As usual, with the exception of some species roses, none are tip survivors in my setting. Even roses such as William Baffin consistently die back each year to 24-30 inches of viable wood. My typical winter nights average -12F to -20F Fahrenheit, with occasional snaps in the -28F to -32F range during January and February (and sometimes December and March). My plants receive sunlight from sunrise to sunset. They are in an open, windswept field with no protection at all other than a moderate snowcover–usually in the 12-15 inch range. When I assess my roses for winter damage, I consider 15 inches of green to be snowline hardy. Anyway, although many of the factors listed by others can certainly contribute to winter damage, I have heard no one mention the devastating effect of sun scald/winter burn. It is amazing to me to look at canes and see them green on the north side and even trying to leaf out, but the south side is completely fried. These canes must always be cut back severely. I would attribute the bulk of my winter damage to cold winds, winter sun, and the reflection of sun off the snow. The worst time of the year for this type of damage is often late February and March, when daytime temperatures start to warm up. It is not uncommon to see this type of sun damage on trees, also. Until 5 years ago I lived in an urban setting with similar temperatures, but I believe the presence of more buildings and trees provided a buffer for my plants and roses such as William Baffin survived with at least a few long canes.

It is interesting to contemplate the reason that some of the species survive so well. Of course I have heard of physiological responses such as super-cooling, but I have noticed something else. Many of the hardiest species have brownish canes or green canes that redden during the winter and then turn green again in the spring. Each fall I witness the canes of some of my seedlings change from green to a red or reddish-brown. These plants often seem to have better winter survival than many of the roses whose canes stay green. It makes me wonder if the color of the canes could be a factor in survival. Has anyone else noticed this?

BTW, Riku-check your Amur Cherry for woodpecker damage. Between my neighbor and I we lost 3 Amur cherries in one winter–all due to girdling from woodpeckers.

Hi Julie,

It makes me wonder if the color of the canes could be a factor in survival.

Anthocyanin pigments might be helping to prevent UV damage, but that’s just a guess. Two other physical factors that I think contribute to hardiness are high degrees of woodiness and the amount and type of waxes in the cuticle.

BTW, your J02-036-1 is doing quite well here. It had a bloom last week and I have used the pollen a couple of times.


Paul, I’m wondering if that late spring cold snap had possibly been to blame, who knows? … our zone 3 climate is just so extreme! Most of my rugosas had wintered pretty good, though a few were knocked back. It’s been a tough spring in most parts of Canada.

PS I owe you an email …


Don, I think you’ve made some excellent points. I agree that woodiness can certainly be a factor in survival, as it is often the older and woodier canes on a plant that survive while newer canes end up being pruned out after a tough winter. Like you, I suspect that bark or a thickening cuticle as the canes age helps prevent dessication. There is also less water in the woodier canes that would contribute to survival. However, I just cut back to 15 inches a magnificent and mature R. setigera. It was an OP seedling that seemed to have better hardiness than most Setigera roses, which are borderline for this area. I thought I was really on to something but I think it was actually survival of a woody cane or two each year that helped it survive as long as it did without devastating winter damage. Who knows why this winter things changed after 6 years of only mild damage. On the other hand, if one looks at the Spinosissima roses (as they are among the group with the best survival), I see extremely flexible, relatively thin brownish canes, covered with prickles, that bend but do not break. Acicularis also comes to mind. Perhaps the prickles, in some way, also contribute to survival–reflection or dispersal of light? The color pigments in the canes may indeed help prevent UV damage–an excellent point. Perhaps some of the more flexible roses have more wax and less water in their canes that would contribute to flexibility and the ability to withstand lower temperatures–another excellent observation. I do not think there is a single mechanism that makes a plant hardy. I think there are both physical characteristics as well as physiological changes that work together to help a plant survive, but I never give up hope when breeding for increased hardiness. I rarely lose a rose now–which I consider a great improvement over many of the roses I have used in hybridizing. These seedlings may not be tip hardy, but nearly all of these roses have survived a winter with no snow cover which occurred a few years ago. There will always be winters–sometimes even for the hardiest roses–that sweep our feet out from under us. I seem to recall someone from Michigan saying that an Acicularis cultivar from the far north did not do well in Michigan due to the fact that it leafed out immediately when the weather warmed and then was cut down by late freezes. Clearly, it was adapted to different growth conditions than in Michigan as its hardiness was unquestionable in the Arctic area. Physical and physiological adaptations in species roses are a product of evolutionary adaptations that evolved over a long period and for specific conditions. Many of the traits and physical characteristics associated with winter survival may be linked. When we attempt our crosses these linkages could be altered or destroyed, leading to our frustration.

Don, the J02-036-1 came through well for Joe Wright and had mixed winter damage here with between 15 and 36 inches of live wood remaining. The plant is looking great now and I hope for a decent flowering this year. Last year the plant was 50 inches tall and 80 inches wide in late September (with a few blooms even at that time). Since your plant is small I would be happy to send you some pollen when it blooms if you wish.

Paul, the very fact that you said that your winter might even have been milder than normal sends up alarm bells for me. I much prefer a consistently cold winter with stable conditions to one with warmer temps. I always have more damage when the winter temperature is variable. Some of the more tender roses may survive while the hardy ones take a beating. We had a cold sunny winter with no real warm period. I find my damage on the whole much more consistent and predictable as compared to the “pleasant” winters. Not as personally nice for me but my roses seem to prefer it that way.