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It’s time to prune those evergreens

Thinning is the practice of pruning individual stems to create a more open, billowy plant and allow light to reach the interior.
Thinning is the practice of pruning individual stems to create a more open, billowy plant and allow light to reach the interior. Observer file photo

Some of you have been eyeing your evergreen shrubs all winter, waiting for the right moment to reduce their size and improve their shape. Well, the moment is here, so sharpen up your shears and prepare to prune.

This work includes evergreens such as hollies, nandina, ligustrum, laurel and boxwood that are overgrown or simply intruding onto driveways, doors, windows or sidewalks. Pruned now, they will be ready to put out fresh growth that will be the best looking foliage of the year. If you wait until spring to prune, after this growth has emerged, you will cut it off. Then, though the size of the plant will be right, you will be left with the oldest growth and will have lost the best of the year’s new.

For now, leave alone shrubs such as azaleas, rhododendrons, camellias, pieris, forsythia, gardenia, cleyera, loropetalum and the like that bloom in winter or spring. They should be pruned immediately after flowering.

Well-established shrubs should respond to pruning with great vigor once they break dormancy in early spring, and this growth will be quite lovely, particularly when contrasted to the older leaves that show their age.

You should approach pruning in either of two ways: shearing or thinning. Both are descriptive of what they accomplish.

Shearing is a simple task usually done with a long-bladed tool such as hedge shears. The aim is to create an even height and shape to the plant. This is most often done with the smaller Japanese hollies when a formal look with a flat top and sides is desired for edging purposes. Shearing is also done to monkey grass in February to allow fresh, better-looking growth to rise. But this does not have to be done every year, just when the older growth starts to look bad.

However, most pruning is done by the act of thinning, which means the removal of individual stems by cutting them back one at a time to another lateral stem or sometimes to the base. This is a very effective way to reduce height without marring the natural shape of the plant. It is effective as a way to clean out and lighten up a plant that has become more of a thicket than an attractive shrub.

Boxwood plants should never be sheared. Light thinning of individual stems is far better because it encourages a denser plant that is billowy rather than rigid. This allows more light to sneak into the interior of the plant and encourage foliage to develop further along the stems, instead of simply at the tips. Thinning is done with small pruning shears, not hedge clippers.

Thinning is also best done to the larger hollies to give a looser, airy look that is very natural to see. It also works well with nandinas, which can become a thicket. Simple removal by thinning of the oldest vertical stems to the base should improve the plant’s appearance and encourage fresh growth.

Ask Nancy

Q. I have heard there is an easy way to get more Lenten rose plants from ones I have already. How does this work?

A. As winter moves into spring, start looking for seedlings around your Lenten rose plants. These can be left to grow larger, then moved to a shady place. They should produce blooming-size plants in three years or so. The flowers may or may not be the same color as the mother plant, but they will be beautiful and useful, not to mention, free.