||Dr. Gouin's Bay Gardener
Pruning Overgrown Yews
Unruly shrubs grow back after heavy shearing
The yew is the commonest dark-green needle evergreen used in landscaping, appearing in both shrub and small tree forms. The needles are flat to the touch, and the plants are generally very dense and compact. They differ greatly from junipers, which tend to have spiny needles, are blue-green in color and generally grow much larger than yews.
In many landscapes, yews are sheared into balls, squares or rectangles. After many years of shearing, they eventually outgrow their usefulness. This is when most home gardeners decide that they must be dug out and replaced. What most people don't realize is that yews can be cut back very severely and still grow back.
Unlike most narrow leaf evergreens such as pine, spruce and junipers, yews are capable of generating new stems from older wood. Cut back a yew plant to stems two to three inches in diameter, and within a month of spring growth, it will produce new branches from near the cut stems. The only other narrow leaf evergreens capable of doing this are the coastal redwoods.
However, when pruning back old overgrown yews, it is important not to fertilize or irrigate the plants. To prevent the rain from irrigating the plants, spread black plastic around the base extending at least three feet on either side of the stem. Severe pruning causes the root system to go dormant, which increases its susceptibility to root rot organisms. Once new growth becomes visible, root activity resumes.
Generally there is no need to fertilize severely pruned plants for several years.
Professor Emeritus Francis Gouin retired from the University of Maryland, where he was the state's extension specialist in ornamental horticulture. Follow his column of practical gardening and plant advice every week, only in Bay Weekly. Ask Dr. Gouin your questions at firstname.lastname@example.org.