Fall and winter rose care
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of the roses that are classified as old garden roses are extremely
tolerant of cold temperatures, while others like hybrid teas
experience considerable damage. Also, budded roses stand a greater
chance of injury or death due to severe cold than do own-root roses.
When selecting roses, always select cultivars that are able to
tolerate the coldest temperatures in your area, based on USDA
hardiness zone maps.
One of the ways to protect roses for the winter is to be sure
they go completely dormant. To accomplish this, stop fertilizing
early enough so growth slows down. No fertilizer should be
applied after Aug. 15. To further encourage dormancy, stop
deadheading or cutting flowers after Oct. 1 and allow the plant
to form hips.
There are many methods to provide winter
protection for roses. The whole idea of winter protection is to
keep the plant uniformly cold and frozen all winter and prevent
the damaging effects of alternate freezing and thawing. Whatever
the method, don't begin covering plants too early. Wait until a
hard, killing frost has caused most of the leaves to fall, and
the temperature has dropped into the teens for several nights.
Prior to covering, remove any foliage or other debris that might
harbor disease for the next season.
Before covering, some tall roses may need minor pruning to
reduce their height, and tie canes together to prevent
wind-whipping. Pruning at this point should be kept to a
minimum. Most pruning will be done in the spring to remove dead
and diseased canes.
The most common way to provide winter protection is to pile
or "hill-up" a loose mix of soil and compost around and over the
plant, about 10-12 inches deep. A variety of hilling materials
can be used, but the key is to be sure the material is well
drained. Wet and cold is far more damaging than dry and cold.
Soil that is used to hill-up plants should be brought in from
outside the rose garden. After the soil mound has frozen, the
mound can be covered with evergreen boughs, hardwood leaves or
straw to help insulate and keep the soil frozen.
A variation of the hilling method is one using collars. An
18-inch-high circle of hardware cloth or chicken wire is placed
around the plant. The collar is filled with soil, allowed to
freeze, then mulched with straw. The benefit of the collar is
that it holds the soil in place all winter and prevents it from
being washed or eroded away.
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Another popular method of winter protection for roses is the use of
plastic foam rose cones. If these are used, they need to be used
properly. First, don't cover the plants too early. Follow the
general timing guidelines. Second, cones need to be well ventilated
by cutting holes around the top and bottom of the cones. This helps
prevent heat buildup on the inside during sunny winter days. It is
also advisable to mound soil around the crown of the plant before
putting the cone in place. For extremely tender varieties, some rose
growers cut the top off the cone and stuff it full of straw for
added protection. It is also a good idea to weight the cone down
with a brick or stone to keep it from blowing away.
Climbing roses offer more challenges. For marginal varieties,
climbers may need to be removed from their supports and bent to the
ground, then covered with 6 inches of soil and mulched. When laying
climbers on the ground for covering, one needs to be very careful
not to injure or crack the stems. As the weather gets colder, their
long stems are more rigid and they are easily broken.
Another method that can be used is to physically pack straw
around the canes while they are still attached to the trellis or
support. The straw is held in place with twine to keep it in place
over the winter.
Generally knockout roses don't require special care in hardiness
zone 5 or south. We are in zone 5b. If you do want to do something
because of prior problems, you can mulch the crown area. Some go to
the extreme and burlap them or put wire around them and fill with
leaves, but that is entirely up to you. The basic care is a pruning,
if needed, in the early spring to size or shape.
University of Illinois Extension]