Fall and winter rose care
By John
Fulton
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[November
29, 2012]
Many
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.
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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.
[By
JOHN FULTON,
University of Illinois Extension]
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