February in Santa Fe is a roller coaster of cold snowy days intermixed with dry mild days. Most of my free time in February, is filled with backcountry ski excursions, my daughter’s swim meets and indoor projects, but occasionally I glance at my garden and get the desire to drag a hose out to water or pull the pruning shears out of the garage. After the deciduous plants have dropped their leaves in the fall, it is a great time to take a peak at the trunk of your trees looking for pests, prune back perennial flowers that you didn’t have time for last summer, or prune out old stems on deciduous shrubs.
Looking for evidence of pests on the trunk and branches on all your trees is a good idea in the winter as discoloration or a change of texture can be more obvious than during the summer months, especially on deciduous trees and shrubs. One of the pests to keep your eyes out for, especially on aspens, is oystershell scale. The protective covering over the eggs of the oystershell scale appear as small grey bumps along the trunk of your aspen trees. If you are able to reach their location, it is good to take a soft plastic pad and scrub them off as the covering is protecting eggs that will hatch in late May or early June.
Winter is also a good time to prune piñon pines while the bark beetle is dormant. Opening wounds (i.e. pruning) during the spring and summer months can make pinons more susceptible to attack by pests, so the best time to prune live branches is during the late Fall and early winter months.
Selective pruning of other trees and shrubs can also be undertaken in the winter. During the winter months, it is easier to spot the older, brown branches of red twig dogwood shrubs as opposed to the newer, red branches, the older branches can be pruned out at any time. The same goes for lavender, the previous summer’s flower stalks can be pruned back at any time. More extensive pruning should probably be left for the spring when the shrubs are ready to put on new growth. Spring blooming shrubs, such as Lilacs and Forsythia, should be pruned only after they flower in the spring as they set the next seasons flowers shortly after they bloom. Roses should also be left alone until March or so, but all trees and shrubs can have the dead pruned out at any time.
–Peggy Wright (Masters in Landscape Architecture)