56 Rose Gardening: winter protection:
Description
This article is from the Rose Gardening FAQ, by Bill Chandler chandler@austin.ibm.com, Jolene Adams jolene@cchem.berkeley.edu, Brent C. Dickerson odinthor@csulf.edu, Karen Baldwin kbaldwin@veribest.com, and many contributors
56 Rose Gardening: winter protection:
Local advice is preferred for this question, but here are some general
guidelines for winter care of rose bushes for those living in colder
climates. The major dangers to the plant in winter are the drying of the
wind, the effect of alternate thawing and freezing cycles on the plant when
winter temperatures fluctuate, the inability of the plant to take in water
if the soil is frozen, and damage from the cold itself to the canes and bud
union.
1. If you live in an area with harsh winters, plant cold-hardy roses. Your
choices are more restricted that way, but you will save yourself a lot
of work and heartbreak. Many once blooming old roses are very
cold-hardy; of the repeat blooomers, rugosas are rock-hardy, and many
Austins and other shrub roses will do okay. Many yellow and lavender
roses are especially tender. Unfortunately cold-hardiness is not an
exact science; conditions such as wind affect roses severely in cold
weather (by drying them out), and so zone ratings are only a first
approximation. Beware of books that rate roses 'cold hardy' or 'not
cold hardy'---they are likely referring to conditions in the UK, which
has mild winters. Beware also of catalogs that overrate cold-hardiness
because they want to move more product.
2. When in doubt, plant own-root roses. If they die back to the ground in
a particularly severe winter, they will grow back from the roots fairly
quickly. This advice is not applicable to once-bloomers, because these
usually flower only on the last year's canes. Own-root Old Roses and
English roses are available. Hybrid Teas are almost always sold as
grafted plants, and it is difficult to find own-root plants.
3. In the fall, reduce the amount of Nitrogen fertilizer used. This,
combined with lower temperatures, will slow the production of new
tender growth, and will allow the existing growth to harden off.
4. Stop deadheading about September 1 for zones 4 and 5. This will allow
the plant to form hips. The formation of hips encourages the plant to
slow down growth, slow blooming, and harden the canes, all preparing
the plant for dormancy.
5. Understanding rose dormancy will help to determine the proper time to
prune during the period from late Fall to early Spring. During
dormancy, the sap has left the canes and they are simply empty tubes of
cellulose. Pruning too early (before the sap runs back) cuts some of
the nutrients out, so you must be sure the plant is dormant before fall
(winter) pruning. Winter dieback generally occurs from the end of the
branches (canes). Pruning removes the available length that can die
back before reaching the ground. Also, pruning a semidormant plant
stimulates growth and sap flow in the pruned region. For a plant going
dormant, this is bad because it inhibits dormancy. For a plant waking
up (springtime) it's good because it stimulates growth. Ideally pruning
should occur before sap is fully flowing.
6. To prevent disease/fungus from overwintering, clean the rose bed by
removing leaves and other debris. Spray the bush with dormant oil to
kill bacteria on the bush and on the ground.
7. Protect the crown of the rose. This is critical since the crown is
where you want the new canes to come from. There are several methods of
protection to choose from.
o Cover the bed at least a foot deep with tree leaves. Do not use
rose leaves as they may harbor disease. Oak leaves are best as
they seem to drain better.
o Cover the bed with straw.
o Use rose cones.
o Make a mound with soil or mulch to cover the crown.
o Wrap the whole plant in burlap if necessary, in addition to one of
above methods of protecting the crown.
Timing is important. Covering the rose too early is unwise as it may
prevent the rose from hardening properly and will slow the onset of
dormancy. Covering the rose too late may risk damage from the cold.
8. Climbers or long canes may benefit from being tied to avoid thrashing
from the wind. Canes may be protected from drying winter winds by
wrapping them in burlap with a layer of straw for insulation. In severe
climates long canes may need to be tied and buried.
9. Keep the soil well-drained, especially as the spring rains come.
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