Just when you think the cold and rain is going to keep you out of the garden until spring returns, there comes a break in the weather. OK, we should not expect a reversal in winter weather but we can look forward to the occasional period of warmer temperatures and even an afternoon break in the cloud cover as each day grows longer. On days when a long-sleeved sweater and a hat are enough to protect us from the chill in the air, we find ourselves venturing out into the garden.
Take advantage of these dry, mild spells to prune dead or diseased wood from deciduous trees and shrubs while their branches are bare. Winter is the time of year when the silhouette of deciduous trees stands out clear. Take out wayward limbs that detract from the shape of the plant. Cut out branches that obviously cause congestion in the branching pattern. This includes branches that crisscross each other and those that shoot back into the center of a tree. Every pruning cut should make sense.
Before you cut, think about the nature of the plant. First, I ask myself why I want to remove a limb or branch or twig. Will the cut improve the shape of the plant? Can I raise the lowest branch of a tree enough for
me to walk under it without ducking down while mowing the lawn? Shrubs that have an open, fountain-like shape should be allowed to develop a natural flow of branches rather than shearing them back into a ball or square.
Once I have decided to make the cut, I ask myself this next question, “How will new growth emerge from this cut?” If you shear a plant into the shape of a ball, new growth will shoot out from every cut you make, forming a bigger ball. Shearing is to cut a plant back with a pair of large scissor-like pruning shears with long handles. A good example is cutting back boxwood in a way that stimulates new growth over the entire shrub. Other plants that benefit from this type of pruning are spireas, heaths and heathers.
Winter is not the time of year to cut back spring-flowering plants. The majority of early-flowering shrubs have already formed their flower buds on last year’s wood. Any pruning will remove the upcoming year’s flowers. Rhododendrons and azaleas are good examples. These plants can be pruned immediately after they flower in spring. The new growth that emerges after pruning will carry the buds of the following year’s flowers.
After the next period of rain, mark any spots where water stands and fails to drain from your garden. Soil that holds water and doesn’t drain is death to more plants than cold, snow and freezing weather. Try digging a shallow drainage trench to see if this will be enough to clear standing water from the area.
If this is a recurring problem that cannot be corrected with a shallow trench, consider installing French drains or some other proven method of soil drainage as soon as possible. If this sounds like too big a project for you, consider creating a bog garden. Japanese iris and several varieties of primrose (Primula ssp.) thrive and multiply when their feet are wet.
In recent years, junipers with lovely form and color have been introduced to the Northwest garden. Both the large shrub junipers and the creeping forms of coniferous ground covers can be pruned now. New, spring growth will quickly cover the pruning cuts. Prune these plants rather than shearing them. Shearing a needled evergreen produces a dense outer layer that shades the inner wood and can result in die-back.
Junipers are hardy plants that look best when pruned along the plants’ natural lines. Cut out branches that grow into walkways or other plants. The easiest way to prune is to take hold of the end of a branch that has grown too long. Follow it into the shrub and cut it off at a point where a healthy branch forks off and is growing in the direction you want the plant to grow. Think about how you prune roses above a bud to force the direction of growth. By removing only the leggiest branches in this manner, you should only have to prune junipers once every few years.
Robb Rosser is a WSU-certified master gardener. Reach him at Write2Robb@aol.com.