January 11, 2014
After the winter solstice and the holidays, deciduous fruit trees, vines and roses beckon us to take up our hand pruners and loppers and get to work. Pruning and preparing plants for spring growth is an important part of winter gardening and pays dividends later.
Roses can be a thorny contradiction, however. While they are simple, beautiful and perhaps as old as gardening itself, roses are also complicated, bred into many thousands of hybrids and cultivars. It all can be intimidating to a beginning gardener.
The history and classification of the genus Rosa is a bit messy and difficult to grasp, which is perhaps part of the intrigue that prompts some gardeners to become rosarians, join rose societies and devote valuable time and resources to their acquisition and cultivation.
The kind of rose, however, does make a difference in how it should be pruned. Rather than try to fathom the Rosa genetic tree, let's instead get down to the basics so that prickly bush in your yard can be efficiently pruned with some degree of confidence.
First off, the gardener should be prepared with clean and sharp pruners, loppers and some good gloves. The modified epidermal cells that we erroneously call thorns are a real menace and the wounds they inflict have a tendency to become infected. A good pair of leather gloves, or even some longer gauntlet gloves, are reasonable protection from these dangerous prickles.
Secondly, the concept of the grafted plant should be understood. There are many old garden and species roses that are "on their own roots," but most modern roses are growing on a rootstock from a different plant. The bud or graft union, if present, needs to be identified and any canes arising from the rootstock eliminated. Not doing so will weaken the grafted variety and in time overtake it. The union is usually a callused swollen area just above the crown of the plant.
Because roses are so valued and complex, the plants often will have labels. So keep them if you have them. The type of rose can then be easily looked up and any special needs addressed. If a label is found, hallelujah! Clean or replace the label, and be sure it is attached to a strong cane to be kept.
As with any woody plant, the gardener will start pruning on "the three Ds": the dead, the diseased and the damaged. Just removing these, along with any suckers from the rootstock, will sometimes simplify a complicated bush or vine. The next things to prune are parts of the plant displaying any of the natural enemies of the rose, such as fungal pathogens such as rust, powdery mildew and black spot.
The goal of the rose pruning is to create a situation in which future growth will maximize sunlight penetration and airflow throughout the plant. With this goal in mind, remove any crossing branches and make clean, angled cuts ¼-inch above desired outwardly facing buds on remaining canes to create an airy and symmetrical shape.
Timing and sanitation should also be kept in mind. Pruning should be timed for late winter season or early spring. Sometime in January is usually best. If pruned too early, a plant might respond with new growth only to have it damaged by a hard frost. All old leaves on the plant or the ground should be removed as they can harbor fungal organisms. Likewise, take care not to injure the canes and anvil-type pruners should not be used.
While these procedures will get the job done, there are plenty of exceptions. For instance, an old garden roses (bred before 1867) that only bloom on old wood are best pruned just after bloom. These would include damasks, mosses, gallicas and albas. Also, some species roses and modern ground cover or carpet roses can be pruned with much less precision, simply shaping them to their desired form.
Additionally, new roses should be allowed to establish their roots before a hard pruning and most climbers should be trained where desired and their laterals pruned back to two or three buds.
If you are interested in learning more about roses, visit the Marin Rose Society's website at www.marinrose.org. Information on rose diseases and abiotic disorders can be found on the University of California Integrated Pest Management roses webpage.