In Idaho, it has been said, that when the forsythia blooms, it is time to prune the roses. But, there is NO rush! I like to wait a couple of weeks after the forsythia blooms, because you never know when you are going to get a few more cold evenings that could frost the new growth. But, even if you did prune early and we did see a few nights below 32 degrees, it is not going to kill the rose. Just cut off any frost damage that may have occurred on the tips of the roses. Roses are very resilient.
Here are a few guidelines for pruning roses in Idaho:
1.Sharpen your tools
2.DISINFECT your tools
3.DISINFECT your tools
4.Rake up all rose refuse and throw it away. DO NOT compost anything from a rose plant.
5.Use hand pruners for small branches, on larger branches use a loppers, on the largest canes use a hand saw. Don’t try and cut a cane with brute strength and a tool that is too small for the job. You’ll end up crushing the cane and having to make a new lower cut.
I say disinfect twice because it is so important. Roses in SW Idaho have been hit hard by Bacterial Cane Blight. You will know your roses have it if the canes are black or purple.
Here is an excerpt from the University of Idaho publication by S.K. Mohan and V.P. Bijman
An aggressive cane blight has been observed in the Treasure Valley of Idaho since 1996. Symptoms were commonly under cool, wet conditions in spring (March to May) and the level of incidence and severity of the disease varied from year to year. Several cultivars of climbing, floribunda, grandiflora, hybrid tea, hybrid perpetual, miniature and shrub roses can show severe symptoms.
Symptoms The symptoms usually started at the base of a vegetative bud or at leaf scars or wounds, as reddish-brown areas on the bark that later turn dark purple to black and necrotic. The necrotic areas expanded around and along the cane, often involving a major part or even the entire cane. Vegetative buds on the affected parts of the cane turned brown and dried. The surface of the necrotic areas of the bark was glossy, and the tissue beneath the epidermis was brown to dark brown, and moist in the early stages. Often confused with winter injury.
Cultural control The following is suggested in the absence of specific research to control this problem.
· Remove and destroy infected stems.
· Disinfect pruning shears before cutting more stems.”