Wintering hybrid tea roses can be a frustrating affair if you’re trying to grow them traditionally with their bud unions only two inches below the surface. At this depth, the above ground canes and bud union are very prone to freezing and frost damage.
So here are four different ways to keep your roses alive over the winter.
Our objective is to stop the bud union from freezing.
The first step is to prune the rose canes back to 12-18 inches in length and spray the surviving lengths with a fungicide to stop fungal problems such as black spot from overwintering.
We can winter hybrid tea roses in several ways:
Traditionally, gardeners have hilled their roses.
This means they bring soil in from another part of the garden and – after cutting back the canes to 12-18 inches long – hill up those canes and bury them with soil. Do not dig the soil from around the rose. By doing so, you’ll lower the soil around the base/roots of the rose and expose them to freezing temperatures.
Some gardeners have hilled with straw, leaves, and peat moss (being the favourites)
Hilling with soil is more work but is more effective.
Constructing cages has become more popular again and constructing a wire cage around the rose and filling the cage with leaves or peat moss is better than hilling with these materials and likely as effective as hilling with soil (assuming the cage is 2-3 feet wide)
Flexible Foam Insulation
Foam insulation was used at the Royal Botanic Gardens in Hamilton (USDA 5/6) quite a few years ago and survival under this flexible foam was excellent.
Nurserymen use this material to protect tender crops and it is available in garden shops. It rips and degrades in the sunlight so do take care of it. It does work in USDA zones 6 and warmer.
In colder areas, I’d be tempted to use a combination of hilling and covering the hill with foam to add an extra layer of protection.
Rose hats come in a variety of sizes and names but they’re all essentially a molded Styrofoam covering that sits over top of the rose and tries to protect it from the weather.
Again, these work in milder climates but in a USDA 4, you have to use the rigid foam under a covering of leaves, peat or soil to make sure it works reliably.
I’ll have more to say on this in other articles but the point is the bud union is planted 4-6 inches deep rather than 2-inches deep. I’ve been growing roses this way for years and have never hilled or worried about winterizing the tender hybrid teas.
The only problem of course is that you’ve already planted your rose in a traditional manner and you’re restricted to the above methods for winterizing
And that’s an important point –
Few of these systems are reliable from year to year. But it is necessary to protect your roses if you are wintering hybrid tea roses.
First thing in the spring, the hills and protection are removed. We don’t worry about frosts hurting the canes, we just don’t want the rose to produce shoots that are too tender and will be burned by cold weather.
It is better to remove the covering a little early than a little late. That’s the conventional ways of wintering hybrid tea roses.