I’m not a fan of bush roses, those frost-tender hybrid teas, grandifloras and floribundas. I find these plants much too capricious and prone to diseases and insects for my taste. But it’s their lack of winter hardiness that totally removes them from the list of plants I might ever want to grow.
The label on bush roses usually accords them a zone 5 hardiness rating, but that’s actually a blatant lie. In fact, they are only fully hardy in hardiness zones 7 or 8, depending on the cultivar. Rose nurseries know this, but “presume” gardeners do as well and that they’ll take special precautions, automatically offering winter protection in colder climates. According to their calculation, a well-protected zone 7 or 8 rose should be able to survive in USDA zone 5 (AgCan zone 6) and thus it’s legitimate to write “zone 5” on the label.
I beg to differ. I firmly believe the hardiness zone for any plant should be its real hardiness zone. It annoys me that this kind of illogical labeling is even allowed. It’s like saying a chocolate doughnut has only 70 calories instead of 450 “because everyone knows you should only eat one bite!”
Now, in appropriate climates, such as south of the Mason-Dixon line in the US and just about anywhere in central or southern Europe, there will be little to no need for winter protection for bush roses. But for gardeners in colder climates, good winter protection is absolutely necessary.
You Already Have Bush Roses?
It’s too late and you’ve already planted bush roses (again, hybrids teas, grandifloras and floribundas)? Perhaps you were unaware that there are hardier roses around and, in fact, a huge choice of them for zones 2, 3, 4 and 5. None need any winter protection if you plant them in their hardiness zone or a warmer one. (For example, you could plant a zone 4 shrub rose in zones 4, 5, 6, 7, 8 or 9, but not in zones 1 to 3.)
For whatever reason, you now have a garden full of zone 8 roses and you live in zone 4. What are you to do now that winter is upon us?
My first suggestion is to simply let them die. I figure that’s always the best solution. Why keep a plant on life support (which is essentially what winter protection is)? You might as well just let it die and get it over with. After all, few of these tender roses live more than a few years in cold climates anyway, in spite of the best winter protection. Next year, just plant something better suited to your conditions and your life as a gardener will be much more enjoyable. (It’s always easier to work with Mother Nature than to fight her tooth and nail!)
But maybe you aren’t yet there yet in your evolution as a gardener? (We almost all start off wanting to grow plants we really can’t and only wise up after the accumulation of bad experiences teaches us it’s a waste of time!) I get that. What follows, therefore, are my recommendations to not-so-laidback gardeners on how to protect bush roses bushes for the winter.
When to Start
Ideally, wait until all growth has stopped on your rose bushes and the leaves have dropped off, usually after several bouts with subzero cold (14 to 23 °F/-5 or -10 ° C). They need to be fully dormant and yet are often very slow to prepare for winter. If you install winter protection too early, before the roses are truly dormant, they often start to put on out-of-season growth under their covering and that can be fatal for the plant when real cold arrives.
But what if the ground has begun to freeze? That’s spot on the right time to start. And if there is snow, just push it aside or wait until it melts (usually the first snows melt away rapidly).
Four Protection Methods
This is the most popular method of protecting roses from winter damage in colder climates. Rose cones are widely available, inexpensive and easy to use. Just make sure you punch a few 1-inch (2,5 cm) holes in the cone near the top (some come pre-perforated) for aeration.
Simply mound up about 6 to 8 inches (15 to 20 cm) of soil at the base of the plant, prune the branches back enough so that they can fit inside the rose cone (therefore, the height at which you prune them can vary according to the dimensions of the cone you use) and the slip the cone over the plant. To hold the cone in place, use stakes, rocks, a brick, etc.
This is the least effective method. A rose cone doesn’t really keep the protected plant much warmer than the surrounding air, at least, not unless there is plentiful snow cover to back it up. What it does do is cut drying winds and moderate rapid temperature swings, both of which are still beneficial. Rose cones really only work effectively in conjunction with snow that falls early and stays long. The result of this rather iffy method is that you find you still lose a number of roses each year, especially when the winter has been exceptionally cold.
Covering With Insulating Fabric
In this method, cover the rosebush and indeed the entire bed with an insulating fabric designed for this purpose, usually a geotextile lined with plastic (Plastified Arbotex is the product professional rose gardeners use). Before you install it, prune the roses severely, down to 8 to 10 inches (20 to 25 cm) in height and remove any leaves or flowers to prevent fungal diseases. Insert stakes here and there so as not to crush the plants when the fabric is covered with snow. Either that or cover them with wooden snow fencing. No mounding with soil is necessary.
This method acts in part by preventing the coldest air from reaching the plant, but even more so, by catching and retaining bottom heat, that is, heat that radiates upward from deep in the earth throughout the winter. Thus, the rose is not only protected from the cold, it is actually heated to a certain degree.
The success rate with this method is much better than with rose cones. The only downside is that rose bushes, having been pruned severely in the fall, don’t necessarily grow back evenly the following summer, so you’ll need to do some careful directional pruning come spring.
This method is laborious, but extremely effective. It is popularly used for tree roses and tender climbing roses.
Next to the rose, dig a trench as long as the plant is high and 12 to 18 inches (30 to 45 cm) deep. Then dig up the plant’s roots and lay it in the trench. In the case of climbing roses, that means detaching the stems from their support and pulling them together tightly with cord. To finish, fill the trench with earth and cover the resulting mound with a good thick mulch. In the fall, don’t prune trenched roses other than to remove any remaining leaves or flowers.
Trenching is the most effective way of getting non-hardy roses through the winter, with a survival rate of nearly 100%. On the other hand, digging trenches is a lot of work each fall … and then in spring, you have to dig up and replace the roses, doubling your efforts.
In Out of the Cold
Another way of protecting tender roses is to pot up your tender roses and bring them indoors out of the cold. This is also the best method for overwintering roses already growing in pots.
Of course, I don’t mean you should bring them indoors to your living room, but rather to put them in some sort of cold storage facility like a root cellar, cold room or slightly heated garage. The temperature should remain near or slightly below freezing, between 15 and 50˚ F (-10 and 10 ° C) for most of the winter. Keep the soil slightly moist, watering as needed. The plants can be stored in the dark since they will be fully dormant anyway. Then replant the rose in spring when there is no risk of frost.
The success rate with this method is excellent, but it too requires a lot of effort if you have to pot up, then replant all your roses each spring.
When Spring Has Sprung
While you don’t need to be in a hurry to install rose winter protection in the fall, you do have to remove it quite promptly in the spring, as covered plants can start to overheat on hot sunny spring days. That can bring the plant prematurely out of dormancy and lead sprouting, yet if that is followed by a frost, it can actually kill the plant. In addition, excess humidity often starts to build under the protection in the spring, leading to problems with fungal diseases. So, as soon as temperatures start to regularly rise above freezing during the day, it’s time to remove cones and fabrics. Do so preferably on a cloudy day or at the end of the day to prevent the still fragile buds from burning or drying out when suddenly exposed to intense sun.
This is also the right season to move outdoors roses that have overwintered in a garage or cold room. And when it comes to trenched roses, stand them upright and replant as soon as the ground has thawed.
Roses for Laidback Gardeners
True laidback gardeners already know better than to plant tender bush roses in cold climates and may already be growing hardy roses, a category that includes most shrub and miniature roses and some polyantha and climbing roses (here’s an article on hardy climbing roses).
And no protection really does mean no protection. There is no need to wrap or cover these tough roses in any way, nor to bring them indoors or bury them. In fact, they need no fall care whatsoever, not even pruning. In fact, leaving rose hips (fruits) on the plants actually stimulate increased hardiness (plus it feeds the birds!).
I hope that this text will help clarify winter protection for roses and that it will satisfy worried beginners who always seem to want to protect every rose they grow, even hardy ones. (You have no idea how many times I hear each fall “how do I protect my hardy roses?”)
And learn to grow plants adapted to your climate and your conditions, and that includes choosing the right roses. It’s simply the easiest way to garden. Life is just too short to waste it wrapping up plants that Mother Nature would rather see die!