The Iowa Gardener: The right way to prune a hedge

Hedges are wonderful landscape assets, providing privacy as well as a green backdrop. Some hedges are small — just a few feet high and a few feet long, while others can soar up to 10 or more feet and go on for hundreds of yards.

No matter what type of hedge you have, it likely will benefit from at least one pruning a year. Pruning helps keep hedges tidy-looking, thicker and can help control size.

When to prune a hedge

Timing depends on the type of hedge you have. If it’s a flowering hedge, wait a week or two right after it is completely done blooming (for most flowering hedge plants in the Cedar Rapids area, that’s June or July).

If a hedge is non-flowering, the best time to prune is now, early spring, before it starts much active growth. That way, it can divert more of its energy into filling out after you prune it.

However, with non-flowering hedges, you can prune them throughout the summer or right after the first hard frost. Just avoid pruning them during the heat and possible drought of late summer and in the early fall, when pruning would stimulate tender new growth that would susceptible to winter damage.

Useful Tools

The following tools are handy when pruning a hedge:

Natural or tightly sheared?

You’ll also need to decide if you want to maintain a loose, casual shape or a tightly sheared or geometric shape. Let the natural shape of the plant help you decide.

For example, many homeowners shear spireas — a mistake. Spireas naturally have a cascading, fountain-like effect. By shearing them, you deform their lovely natural shape and also trim off developing flower buds. That’s why sometimes, even with shearing, they’ll send out only a few, sparse, oddly spaced flowers in spring.

Other common hedge plants that do best if allowed to maintain their natural shape include juniper, arborvitae, lilacs, burning bush and honeysuckle.

Good candidates for tidy geometric shapes include boxwood, privet and yews — they all have dense shrubby growth that responds well to shearing. They also are fine if allowed to assume more of their natural shape.

With other hedge plants, do some online research first on the best method and timing for that plant. Each one varies.

How to prune hedges

With any type of plant, the first step in pruning is to remove any dead or damaged wood.

With plants where you would like to maintain their natural shape, go in with a hand shears and loppers to do something called “selective pruning.” Trim branches to neaten and shape the plant as desired. As much as is practical, try to shape the plant so that the top doesn’t block sun from the bottom branches, or else you’ll eventually have a hedge that is vigorous on the top but has no leaves on the lower parts.

With plants that you are shearing, first go through and cut back any larger branches, those a half inch or more since the hedge shears won’t get those. Then follow up with the hedge trimmers.

Pruning can be used to control plant size, but it’s a tricky proposition that can affect the overall attractiveness of a plant. It’s best to plan ahead, when possible, to choose and position plants so they can achieve their full size and don’t need to be kept in check with frequent, hard pruning.

If a hedge is several years old and severely overgrown, do some online research on how to rejuvenate it. With some shrubs, it’s as easy as cutting them down to just a foot or so and then allowing them one to three years to regrow.

Veronica Lorson Fowler is co-publisher of The Iowa Gardener at www.theiowagardener.com