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Putting Roses to Bed

© Mary Henry

It's time to start preparing the roses for winter and I'm feeling especially proud of myself this week. I planted five new rose bushes this year and I won't have to cover or bury a one of them. Coming to Minnesota from zone 6, I was astonished at the machinations local gardeners go through in order to grow tender hybrid teas, floribundas and grandiflora roses. The Minnesota Landscape Arboretum makes an event of Laying Down the Roses in the fall and Raising the Roses in the spring. At the Lake Harriet Rose Gardens, where there is neither the space nor the manpower to lay all the roses down, they mound soil over the graft union and fit the roses with individual corrals that are filled with insulating material (usually chopped leaves). At the garden center where I work, customers are already buying the styrofoam rose cones that they will use over their tender roses. Through all this flurry of work and worry over their prized plants, the questions customers ask now and the problems they bring to us in the spring tell me they don't really understand the process they are using. The program I saw recently on a local TV station about burying roses showed me why they have problems. Let's set the record straight so that we can more easily and safely keep tender roses.

No matter how you protect your tender roses, by building a pen to hold insulating materials, covering with a styrofoam cone or burying them in a trench, the most important part of the job is letting the plant go naturally dormant. Wait to do your covering until the early freezes have signaled the plant to harden all new growth, drop its leaves and go into its dormancy just like the hardy ones do. Remember, it will survive in zone 6 (-10º and frozen ground) if allowed to do this in synch with the changing weather.

All the tea roses that I see for sale in Minnesota (zones 3 and 4) would have grown in zone 6 with no winter cover. There are some roses too tender for zone 6, but I never see those offered in Minnesota because most of them flower on old wood only, and there is never going to be enough of that here to make them worthwhile. I refer to zone 6 to make the point that all these roses are hardy to at least -10º, the average minimum there. Everyone here in Minnesota (including this TV horticulturist) seems to believe that the roses must be put down or otherwise protected before they experience any frost. This is not true! The roses need to experience frost to complete their trip into winter dormancy. When the leaves are gone, there is almost no need for the fungicides that are always recommended before burying the plant. The lime sulfur usually recommended for this is, I believe, more dangerous for the homeowner to handle than its use would warrant. With more and more alarming information becoming available about the dangers of fungicides to the environment, it is truly best to let the leaves fall naturally thus removing the source of the infection. This was the sight that so astonished me on the TV program - a rose bush in full green leaf was being hustled into a hole in the ground to spend the winter. The bush was not only not dormant, but still actively growing. It will experience a delay in going dormant now that it is insulated and may even form tender new growth beneath the covering that will rot along with the leaves.

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