Don’t Be Afraid To Prune Perennials

One of my favorite spring chores is pruning ornamental bushes and shrubs to get them ready for vigorous spring growth. I’ll throw in the caveat that pruning wild rose bushes is not a favorite chore. Even with special gloves made for rose pruning, I manage to stab myself around my upper arm, legs and shoulders. These are some pretty big bushes!

My husband and I have different philosophies on how to prune. He tends to cut a lot of the plant, but does a great job of shaping trees. I tend to underprune and some of the bushes look leggy, with too little growth on the lower portions of the branches. So we try to temper each others’ approaches.

spring blooms in xeric garden
Spring means the apple tree along the river (background) blooms big. It also means time to prune. The green plant in the left foreground was almost as tall as the red bud to the right only a few weeks before.

The best approach, especially in xeric gardens, is to follow the plant’s natural growth pattern. This means avoiding the “haircut” prune, or cutting a plant straight across the top. It’s like topping trees; it makes me crazy. A haircut prune on a bush forces new growth only along the top of the plant.

For deciduous shrubs (those that lose leaves in winter and come back in spring), pruning should include thinning to make sure sun reaches bottom branches and to prevent crossing or rubbing of branches. Gradual renewal pruning involves removing dead and old branches just above ground level each year. You also can trim to shape long branches.

Rejuvenate old plants by cutting up to one-third of the oldest and tallest branches just at or above ground level before new growth starts. Here’s the thing, though: Although experts generally warn against pruning an entire plant all the way to the ground, I have done that for several established woody plants that get long and leggy and have few flowers. I’ll even do it annually with great success.

For example, I trim Russian sages (Perovskia atriplicifolia) to just a few inches above the ground, or just above new growth, each spring and they love it. We had a hibiscus (I’m not sure of the variety, but see below) that we pruned to the ground each fall to help it winter over in Albuquerque. It came back in the spring, with huge, maroon-colored blooms that would cause people to stop on their walks and comment.

hibiscus-pruned-nm-landscape
We trimmed this hibiscus, the plant with the large, deep read blooms, to the ground in the fall to protect it from frost and to produce foliage and blooms.
hibiscus-flower
The hibiscus blooms were beautiful and continuous from mid-summer to early fall.

 

Finally, I trimmed an old and overgrown butterfly bush (Buddleia davidii) to just above the ground last year, and by the end of summer, it was more than six feet tall and full of deep purple blooms, butterflies and hummingbirds.

Butterfly bush trimmed back
Butterfly bush (the woody plant in the back of the first bed) cut back last year nearly to the gtound.

 

Butterfly bush after hard pruning
Here’s the same bush in September from the other side. It’s happy, and so are the hummingbirds and butterflies.

Every plant differs in just how much to prune and when to prune it. For example, most of our xeric plants enjoy a cut in early spring. I wait until I see a little new growth appearing and then bring out my pruning shears. But we have a few forsythia bushes, which bloom early, but should be pruned after they bloom. And most evergreen shrubs need only some thinning.

Be sure to use clean bypass pruners and loppers on your plants, and clean after each use, especially if you cut any diseased branches.

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