© Janet Davis
Depending on what type of roses you grow, winter is either a scary prospect or
no big deal at all. Mid-November to December, just as the ground is
beginning to freeze hard, is the time to protect tender roses that need
insulation near the vulnerable graft or bud union (the knobby bit) at the base
of the plant. The bud union is the result of grafting an otherwise tender rose
onto much hardier rootstock -- often Rosa multiflora, a tall, small-leafed rose
with sprays of tiny white flowers, which is what new rose-growers often
complain has replaced the pretty pink or red rose they planted. In a cold
winter with inadequate snow cover, an exposed bud union shrinks and expands as
the wood of the rose freezes and thaws. The best way to prevent that is to
insulate it.
Tree roses: In the "very scary" category are tree roses.
Unless you live on the mild west coast or south of Can. Zone 7 (U.S.
Zone 6), they are vulnerable to winter damage.. If you have one, you have two
options. Dig it up, being careful not to disturb the root ball, then transplant
it into a big pot which can be stored in a cold, but not freezing garage and 
kept lightly watered 'til spring. Or loosen half the
roots on one side of the rose, dig a trench away from the other side, then bend
the entire rose into the trench, covering it with soil and then a thick layer
of autumn leaves.
Hybrid Teas, Grandifloras,
Floribundas, David Austins, Climbers:
Depending on their parentage, many of these large-flowered lovelies have
tender bloodlines that make them poor risks to withstand the extreme lows of
our winter. Even grafted onto hardy rootstock and mounded to the hilt, they
sometimes succumb. Nevertheless, the
best way to protect these large-flowered lovelies is to mound at least 12
inches of soil (topped, if desired, with autumn leaves) around their base. Wait
until there's been a good, hard freeze so you know the rose is dormant, then
tie back climbers and cut back the canes of bush roses to three or four feet.
If mildew or black spot have been problems, experts recommend stripping leaves
off the plant and raking them up to help eliminate the chance of
reinfection. Use soil to mound the
roses from other areas of the garden so as not to expose the roots or create
dips where water collects and freezes. The soil you use should be regular
garden soil. Some rose-growers use manure in this soil to give the rose a
jump-start right after spring thaw. Many use plastic, metal or fibre-glass rose
collars to contain the insultation material.
In spring, remove the soil layer by layer (in case of late
freezes) and wait until it's warm to do yourr hard pruning. The wood that
survived will have white inner pith and the canes will "green up"
slowly to the winter-kill point. Then you can do your normal spring pruning.
Shrub Roses: These are the hardiest roses, often grown on their own
roots and can generally go without protection. The best for cold-winter
climates are the Ottawa-bred Explorer Series and the Manitoba-bred Morden
Series.
Adapted
from a column that appeared originally in the Toronto Sun