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Question: We have a row of boxwood plants along one side of our patio. They were planted three years ago and are doing well. We haven't done any pruning since we got them, and as a result, they're starting to look a little unkempt. When is the best time to prune them and how do we do it? Is it best to use an electric hedge trimmer or would one of those long-bladed shrub trimmers work? Also, will we need to prune every year or is every few years enough?

Answer: Boxwood (Buxus spp.) is a great shrub for the Western Pennsylvania landscape. There are dozens of different species and cultivars, with many varieties being fairly easy to find on the market.

Boxwood is evergreen, winter hardy and deer-resistant. And though some species can succumb to a recently introduced pathogen called boxwood blight, overall, they're a plant that isn't plagued by a large number of pests and diseases.

I'm glad to hear your new boxwoods are doing so well, and I'd like to offer you a few tips to increase your chances of continuing that success long into the future.

First, you were smart to allow the plants to grow for a few years before attempting to prune them. Pruning can put a good bit of stress on a plant, causing it to put a lot of energy into making new growth to replace the growth that was trimmed off. By leaving your newly planted boxwood untrimmed, you helped encourage the plant to expend that energy on developing a good root system instead. But, now that three years have passed, it's time to develop a regular pruning regimen, if you want to maintain the plant's natural shape and limit its size.

Good boxwood pruning takes three factors into consideration.

1. Good sanitation. Since boxwood blight can readily be transmitted from plant to plant via contaminated pruning equipment, good sanitation is key.

Do not prune your boxwood with an electric hedge trimmer, or even a long-bladed lopper. Instead, use a pair of hand pruners and sanitize them before going from one plant to another, to prevent the spread of disease.

I apply a disinfectant spray such as Lysol to all parts of the pruner, especially the blades, before I start pruning a new shrub. And I don't just do this for my boxwood; I do it when pruning all the trees and shrubs I work with.

2. Thoughtful pruning. A properly pruned boxwood should look like it hasn't been pruned at all.

Trimming any shrub into a tight, perfectly round orb is not good for the health of the shrub nor is it attractive. Instead of shearing your boxwoods into green meatballs, judiciously prune them to remove the terminal portion of the stems in a fashion that reduces its size but still maintains the plant's natural shape and form.

Cut a few branches, then stand back to examine the shrub before doing any further pruning. As you prune, regularly examine your work; you can always take more off, but you certainly can't reattach what you've pruned off if you take things back too far. Limit yourself to removing no more than 1⁄4 of the total plant height in any given year.

3. Good timing. Boxwoods are fairly flexible when it comes to the right time to prune them. The only time to avoid is late summer or fall.

Pruning that late in the season generates new growth that will not have time to harden off before winter's arrival, making it more susceptible to winter die-back. I prune my boxwoods in the spring, just before their most active period of growth.

Ideally, your boxwoods should be pruned a small amount every year, to maintain their shape and keep their growth even and well branched.

If you neglect this job for multiple years, the plants will require a more drastic “haircut” and it will be tough to prune them in a visually pleasing fashion.

Horticulturist Jessica Walliser co-hosts “The Organic Gardeners” at 7 a.m. Sundays on KDKA Radio with Doug Oster. She is the author of several gardening books, including “Attracting Beneficial Bugs to Your Garden: A Natural Approach to Pest Control” and “Good Bug, Bad Bug.” Her website is jessicawalliser.com.

Send your gardening or landscaping questions to tribliving@tribweb.com or The Good Earth, 622 Cabin Hill Drive, Greensburg, PA 15601.

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