1 - Rose pruning in fall is discouraged.
Q. I was told that I should not prune my roses in the fall. They have gotten large and block my sidewalk. They need to be pruned. Why is it recommended that they not be pruned now?
A. The roses most commonly grown in New Mexico (and elsewhere) are hybrid tea, floribunda, and grandiflora roses. One of the ancestors of these roses is the China tea rose which is from tropical regions and does not confer dormancy on its offspring. These roses stop growing when the weather cools, but are ready to grow as soon as warm weather resumes. In New Mexico we often have periods of warm weather in late winter followed by cold weather. If the roses are induced to grow by these warm periods, the new growth may be killed when cold temperatures return. If the roses have been pruned, there may be no buds left to replace those injured by freezing. The rose shrub may die or the new growth may develop from the rootstock. The rootstock does not usually produce flowers as desirable as the variety that was grafted onto it.
Delaying winter / spring pruning until about one month before the expected last freeze in your area will reduce the chances of extreme damage to your roses. However, if your plants are so large that they must be pruned now, it is OK to prune them enough to clear the sidewalk. However, save the final pruning for late winter. If warm weather induces early growth, the buds that grow first will be those at the ends of the remaining stems. As they grow, they will produce hormones that delay growth of buds lower on the stems. Those buds whose growth was delayed will be uninjured by freezing weather after growth begins in the upper buds. Buds that began growth early can be pruned sacrificially at the proper pruning time (one month before expected last freeze) even if they were not damaged by freezing. If they were frozen, then they were effective agents in protecting buds below them.
Summer pruning, that is, cutting long-stemmed roses for indoor use, or cutting long stems when removing faded flowers is a good way to manage growth that interferes with sidewalk traffic. Such summer pruning to manage growth is a good practice.
There are some roses that do not have the same heritage as the hybrid tea roses. These roses are more likely to develop true dormancy and sufficient hardiness to survive the weather that "tricks" the hybrid tea roses. If you are not certain about the genetics of your roses, it is safer to delay pruning than to prune them too early.
Marisa Y. Thompson, PhD, is the Extension Horticulture Specialist, in the Department of Extension Plant Sciences at the New Mexico State University Los Lunas Agricultural Science Center, email: firstname.lastname@example.org, office: 505-865-7340, ext. 113.
For more gardening information, visit the NMSU Extension Horticulture page at Desert Blooms.
Please copy your County Extension Agent and indicate your county of residence when you submit your question!