With few exceptions, evergreens (conifers) require little pruning. Different types of evergreens should be pruned according to their varied growth habits.
Sometimes you must prune evergreens to control their size. This is unfortunate since, ideally, the right evergreen would have been chosen for the right space, so that you wouldn’t have to do much, if any pruning, for space reasons. But if you must prune, read on.
Evergreens naturally have a beautiful and tidy shape. It’s best to prune them as little as possible, except to remove any diseased or damaged wood. Also, with some evergreens, as they age, the lower branches tend to brown and die. Trim that out
Some other evergreen pruning tips:
- Prune evergreens just about any time of year, except in late summer and fall. Late-season pruning encourages a flush of tender, fresh growth that will more easily be zapped by winter cold.
- Many evergreens are damaged by winter cold and winds. This is called winter burn. They are also damaged by deer. When die-back or deer damage occurs, trim off just the dead part. Then do a light shaping to balance the form of the tree. However, except for boxwood, holly, and yews, most evergreens can’t take a hard cutting back. They won’t regenerate from that interior wood. They’ll just be misshapen.
- So if a plant is very damaged from winter die-back or deer damage and it’s not a boxwood, a holly, or a yew, sorry, you can’t do a major cutting back to restore its shape. It’s best to dig it up and pitch it.
- But do give it a chance until about June. By that time, whatever is going to grow back has grown back, and you’ll be able to see more clearly what you’re dealing with.
- Spruces, firs, and Douglas firs don’t grow continuously but can be pruned any time because they have lateral (side) buds that will sprout if the terminal (tip) buds are removed. It’s probably best to prune them in late winter before growth begins. Some spring pruning, however, is not harmful.
- Pines have a single flush of tip growth each spring and then stop growing. Prune before these “candles” of new needles become mature. Pines do not have lateral buds, so removing terminal buds will take away new growing points for that branch. Eventually, this will leave dead stubs.
- Pines seldom need pruning, but if you want to promote more dense growth, remove up to two-thirds of the length of newly expanded candles. Don’t prune further back than the current year’s growth.
- Arborvitae, junipers, yews, and hemlocks grow continuously throughout the growing season. They can be pruned any time through the middle of summer. Even though these plants will tolerate fairly heavy shearing, their natural form is usually most desirable, so prune only to correct growth defects.
- A few evergreens actually benefit from regular trimming. Boxwoods, hollies, and yews—both used in topiary—tend to do best with at least an annual light trimming to encourage more dense growth.
Source: University of Minnesota Horticulture Extension, Mike Zins and Deborah Brown, Pruning Trees and Shrubs, Item # 00628, 1997, All rights reserved
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