Fall and Winter Care For Shrub Roses
As most rose gardeners know, these thorny landscape favorites grow on canes, each of which has a life cycle. Shrub roses are no different: canes go through phases of rapid growth, followed by abundant flowering, and then eventual decline into either woody, non-blooming growth, or death. The key to healthy shrub roses, then, is in pruning out the old in order to constantly renew the canes, and create the greatest number of new, flowering canes.
This is a task best accomplished in fall and winter, when it is easiest to see the different canes in the plant in relation to one another. Selecting only the healthiest, disease-free and undamaged canes at the base, and clipping above the nodes where new canes will grow in spring, will usually result in vigorous, abundantly-flowering, and disease-free plants. Take care to let the middle of the plant “breathe” with a nice, open scaffold, as this helps stay the risk of disease spreading between leaves. Additionally, clipping a plant down to ⅓ or ½ of it’s original height will help brittle branches withstand against bitter gales.
As for diseases, in autumn, beyond taking care of the shape and the growth of the plant, it is also vital to take care of the soil conditions that nurture potential bacterial or fungal pathogens. Diseases like black spot (Diplocarpon rosae) infect leaves during the growing season, and then the spores drop to the soil in winter, only to reinfect the leaves with “backsplash” from water hitting the soil. Cleaning up leaf litter and other detritus around the base of the plant will minimize the potential of this and other diseases spreading among your roses, even without the use of fungicides.
That said, a healthy heaping of mulch mounded around the base of a rose plant will help the plant retain heat around the root ball and lower canes. Provided the mulch is disease-free and not made of rose leaf litter, and that is is removed in spring, it should not cause any problems for the dormant plant over winter.
With just a little bit of work, shrub roses can be kept in tip-top blooming condition for years.