Although roses are still blooming in our Mediterranean climate, there is a definite nip to the air, as the days shorten, and nights are cooler and moister. While it is a time to lessen one’s chores in the garden, there are a few things you can do now to help your roses get through the winter.
Winds can wreak terrible damage to roses, and they most certainly will come. Low growing roses such are minis are fine, but those tall growing grandifloras and hybrid teas are prime targets for winds breaking off canes or uprooting entire plants. I have some plants (‘Cajun Moon’, ‘Dick Clark’) that have actually grown above my roof line, even though they are not climbers. Long before pruning time, I cut them back by 50% and stake the newest growth.
Cutting off Blooms
Many people love the multi-colored hips that fall and winter produce, but there is a danger in leaving your blooms on the bush. Roses left on the bush can become diseased by botrytis blight, which can start out as pink spots (see photo below left).
Over time, as the disease progresses, petals turn tan and wither, and what was once a bloom can become this glob of grey mold (see photo right). Once established, there are very few organic controls for this disease other than exceptionally thorough sanitation methods – removing spent blooms, cleaning up leaves and petals off the ground, good air circulation, no overhead watering, and removal of old mulch. If you already have this disease, do not compost the blooms and debris. There are a few organic sprays one can use, such as Serenade and Mycostop (broad spectrum biofungicides). If you still want to have hips and do not have this disease on your roses, you can remove the petals from the bloom and hips will still form on some roses.
In our area, it is generally accepted to stop fertilizing, particularly nitrogen, in September. New growth in our climate can be subject to more disease, frost damage, wind damage, etc. and you want your roses to get some rest and dormancy (very little is possible here in Marin County) before pruning.
While the benefits of mulch are numerous (moisture retention, weed suppression, etc.), mulch also insulates the soil and affects soil temperature. Although we don’t have to worry about extreme freezing and thawing of the soil, there are those that say mulching in the fall can fool the plant into a late growth spurt. Whether you choose to mulch now or in the spring, be sure to leave a gap around the base of the plant in the spring so that the sunlight can reach the soil.
If you have done all of the above, you can rest and not worry about your roses as the winds howl outside during the winter months. It is time instead to peruse those catalogs and Internet sites, dreaming of all of those interesting and exciting new roses!
Gail Trimble, Master Rosarian