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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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- Cover the bed with straw.
- Use rose cones.
- Make a mound with soil or mulch to cover the crown.
- 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.
- 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.
- Keep the soil well-drained, especially as the spring rains
come.
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