4 minute read
Winter Rose Protection
Winter Protection by Diane Brueckman
It’s that time again! Our roses need to go to sleep for the winter. Modern roses are bred to be bloom machines, so it is up to us to protect them from themselves. Mother Nature does her part with the shorter day length and colder temperatures. Now is the time for rosarians to do their jobs. In September, we stopped fertilizing the roses with quick release nitrogen and we slowed down deadheading. It is OK to 123rf.com remove dead and diseased canes from your roses but do not cut back canes to shape the plant.
THE GARDEN IS CALLING. DIG IN.
October is the time to stop deadheading. Pluck the petals off the rose to keep the plant looking neat but leave the ovaries to become rose hips. Forming rose hips will tell the plant it has done its job by producing seed. Keeping your roses well hydrated going into winter is very important. You don’t want roses to be under stress because of a lack of moisture. The one inch of water a week rule is sufficient in fall. Roses are not growing as much and the heat is not as intense. It is important to keep up with disease control so the roses go into winter as healthy as possible. When temperatures drop and humidity is still present botrytis blight and powdery mildew are likely diseases. Botrytis blight is very unsightly and hard to miss seeing. The infected blooms are covered with a brown mold, which are the spores. The “cure” is cutting the infected stems off and discarding them. Powdery mildew is a white coating on the buds and new growth at the top of the plant. As for powdery mildew, neem oil is very effective, again cut off the infected stems and discard. Good housekeeping in the garden goes a long way to preventing disease. Removing diseased leaves from the ground takes all those overwintering spores away. Late October and early November is when we can expect a killing frost. Roses will stop growing when the soil gets cool. This is when I start cutting back my roses. Some say not to cut back until spring but I have always cut back in fall. I take out spindly canes and crossing canes because it makes it easier to cover the roses when the ground has frost in it. I also strip all the leaves from my plants. On a warm day with temperatures in the mid-forties, I spray with horticultural oil or neem oil. If I use a light horticultural oil I will add insecticidal soap. Neem oil is an insecticide so insecticidal soap is not necessary. Cane borers over winter in the cane to chew their way out in spring as a mature sawfly to start the cycle all over again. While you cut back the roses look
for holes in the canes. Cut the canes back to solid pith and you will eliminate some borer damage. After several heavy frosts it is time to cover the roses. If the ground is frozen all the better. The purpose of covering the roses is to prevent the freeze thaw cycle, which happens all too often in St. Louis, from forcing early bud break. When the temperatures are in the 60s the ground heats up and the buds start to break on the canes. If this happens the roses can be weakened and die. Cover the roses with 8 to 10 inches of mulch. The double ground hardwood mulch is very effective and usually stays put all winter. Other mulches would be compost or shredded leaves. Both of these mulches need to be checked periodically. They may compact or be blown off the plants and need to be replenished during the winter. Remember do not uncover until the danger of frost is past. See you in the spring!
Diane Brueckman is a retired rosarian with Missouri Botanical Garden, and currently owns Rosey Acres in Baldwin, Illinois. You can reach her at (618) 785-3011 or droseyacres@ egyptian.net.
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