Pacific Northwest Pruning with Mike Darcy

October 2, 2017

From the hot dry summer we just had, the fall season is a welcome relief to both me and my plants. I love this time of year when the days are warm and the nights are cool. This past weekend, I spent time in the garden to do some much-needed pruning and general maintenance.

In our Pacific Northwest climate, it seems as though plants always grow larger than what the tag on the plant says. Many other gardeners tell me this occurs with their plants too and when a tag indicates a height of six feet, the plant may easily grow to eight feet or more. Often times this means that the plant has to be pruned to the desired height. These past few days, I have spent many hours pruning established shrubs and herbaceous perennials and a tip that I would always offer is to make sure your pruning shears are well-oiled, that the blades are sharp and to wear a pair of gloves.

Sometimes gardeners use language that not everyone understands and this language is not to confuse but is just the everyday talk of gardeners. Let me start with the words “herbaceous perennial“.

Herbaceous Perennial: This generally refers to a plant that is a perennial, with the word perennial meaning the plant will survive the winter and come up again in the spring.

We have many plants in our gardens that this term would apply to and a good example would be the common peony. The peony is winter hardy, blooms in the spring, and generally, the stems are cut back to ground level in late summer or early fall. Other similar plants would be perennial phlox, delphinium, artichoke, hardy ginger, asters, gaura, gunnera, rudbeckia, etc. In my garden, as long as plants are still looking good, I usually wait until after the first frost and then prune.

With roses, there is a common saying that roses should be cut back waist high in the fall and knee-high in the spring. With many garden roses still blooming, it can be a difficult choice to cut them waist high now and probably no good reason to do so in our mild Willamette Valley. As the autumn season progresses, and in areas where there are strong winds, the reason to cut roses back to waist high now is to help prevent the plant from rocking back and forth and thus loosening the roots. This is also a good time to observe the plant and remove any weak canes.

Recent research has shown that it is usually best to not seal the stems of plants with a sealant. If you look through old garden books, you will read that sealing the stems of plants, especially roses, after they have been pruned is a necessity when in actuality it is best to let the plant heal naturally.

Do not take pruning too seriously unless you have a “specimen” tree or shrub as plants have an amazing ability to naturally correct mistakes. I keep stressing that gardening should be enjoyable, even pruning.

Specimen: This refers to a plant in a garden that is often a focal point and probably has some special meaning to the owners. Usually a tree, but could be a shrub. I have heard gardeners refer to a Japanese maple as a “specimen” and it might be a tree that they have had for many years or perhaps one that they feel is outstanding in their garden. I have friends that have a Stewartia which is a tree with beautiful colored bark and in the winter when the leaves have fallen, they have a spot light at the base and they refer to this as a “specimen”. A “specimen” tree is a plant, that you the gardener, designate as something extra special in your garden.