Believe it or not, my rose garden will enter the earliest stages of dormancy within a week or so. This is part of the life cycle of roses and other plants when growth, both above and below ground, is temporarily suspended. Two basic environmental cues – diminishing daylight and cooling temperatures – trigger this annual phenomenon. By August 21, in my zone 6 rose garden there will be 1.5 hours less of daylight than there was on June 21, the summer solstice. The amount of daylight continues to drop by 3 minutes daily. At that rate, over an hour of daylight is lost in August alone. Add in the cooler nighttime temperatures common in late August, and rose bushes start to feel a little sand in their eyes; the first sleepy whiffs of dormancy have arrived.
This is a good thing. Roses and other plants that experience a long gradual descent over several months into dormancy will tolerate winter conditions much better than plants pushed into late season growth, usually over-stimulated by late fertilizing. I fed my roses for the final time last weekend, the last of four light feedings, roughly 60 days prior to first frost. Each bush now has enough nutrients stored in the roots and canes to see it through the end of the season and well into the following season. This goes for tough, burly shrub roses as well as dainty hybrid teas.
Once clear of intense mid-summer heat that may have caused a temporary slow down in rose metabolism, the autumn bloom is the last hurrah.
I stop deadheading spent blooms – another form of pruning that stimulates end-of-season growth that won’t have time to mature — in the fall after the autumn bloom cycle goes by. The process is gradual. Some years my cool shady garden is completely dormant by the end of October; other years it’s closer to mid-November. Some years, not often, but if hard frosts hold off, it’s possible to have fresh roses from our garden on our Thanksgiving table.
Dormancy is a rose’s defense against bitter cold and wintery weather and it’s starting now. The trick, then, is to keep roses dormant throughout the winter season. More on that later.