Spring pruning helps maintain shrub health

By Ted Schaaf
Gardens on Spring Creek

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As we approach the first day of spring on March 20, getting outside and doing something in our landscapes is on every gardener's mind.

Shrub pruning not only satisfies that need, it also improves the health of the shrubs. Woody plants, especially shrubs, are the backbone of every landscape. Unfortunately shrubs also tend to be the most neglected plants in our landscapes.

The basics

Hold on to your hats. It may come as a surprise to some that pruning stimulates growth. You heard me right. If your main goal in pruning is to control the growth of your shrub, then you're putting a lot of energy into a doomed project. The end result will either be the slow decline of the shrub or the shrub winning out because you just give up.

With this in mind, the first step in caring for your shrub is not pruning. Rather, it's in the selection of the plant. Placing an 8-foot spreading juniper next to a driveway or sidewalk will mean constant pruning just to keep it in bounds. A 10-foot shrub in front of a window will present the same problem. Because we are fortunate enough to have an extremely large palate of plants to choose from, the best course of action in a situation such as this is to remove the shrub. The empty space in your landscape will present new planting opportunities.

The next step is to learn everything you can about your shrubs. With this knowledge and pruning tools in hand, you are ready to begin.

When to prune

Knowing that pruning stimulates growth, springtime is by far the best time to prune shrubs. Pruning in the spring also allows you to easily see where you're pruning and what branches you need to remove to maintain the health of the shrub.

I've seen far too many landscapers wait and prune shrubs in the fall. This brings about a flush of new growth. Then as we move into winter, this new weak growth can open up a host of problems. Not to mention that some of the shrubs being pruned are ones that bloom on old wood. Pruning them in fall can ruin hopes of seeing flowers the following spring.

Some of the shrubs that bloom on last year's growth include forsythia, lilacs, many of the large shrub roses, spring blooming spireas and viburnums. Be aware that these shrubs should not be pruned until the flowering season is over.

Some shrubs that bloom on new growth include potentilla, blue mist spirea, summer-blooming spireas, ever-blooming shrub and hybrid tea roses. These shrubs respond well to spring pruning.

Pruning isn't shearing

The most common method of pruning is often referred to as shearing. Many homeowners remove all top growth as if they're giving the shrub a haircut. It's even done by landscapers who should know better.

Shearing shrubs creates a dense canopy that totally shades out the inside growth of the plant. For every branch cut, the shrub responds by sending out at least three more stems. This type of pruning, over time, can destroy the natural beauty of the shrub.

Some shrubs, such as red twig dogwoods, respond best by removing one third of the stems all the way to the ground. New stems appear during the growing season. Removing the oldest stems, as shown in the photo above, keeps the shrub from losing its bright red stems. (A major reason why this plant is used in landscapes is to provide winter interest.)

Other shrubs respond well to total rejuvenation pruning. This type of pruning is not for the faint at heart because it requires the total removal of the plant down to two or three inches from the ground. Old and neglected shrubs often respond well to this type of pruning, as do ever-blooming shrub roses. Be ruthless with your rejuvenation pruning and you'll be rewarded with countless blooms.

Heading back a shrub often helps to restore balance to shrubs that send out unruly branches. It requires removing part of a stem on the shrub and should not be done to any more than one-third of the plant stems.

The good news about shrub pruning is that not all shrubs require yearly pruning. Instead, prune shrubs so that they can reach their full potential. They will respond by returning year after year to grace your home with their beauty.

If you would like to learn more about shrub and tree pruning, the Gardens on Spring Creek is offering a class on March 28 from 9 a.m. to noon. Our city forester will do some hands-on pruning out in the gardens. Call the Gardens at 416-2486 to register for this and other classes. The web site is www.fcgov.com/horticulture.

Until next time, happy gardening!

Ted Schaaf is the horticulturist for the city's Gardens on Spring Creek, located off Centre Avenue about a half mile south of Prospect Road in Fort Collins. He works in a 1,600-square-foot greenhouse with dedicated volunteers.