Regional Gardening Reports :: National Gardening Association

In the Garden:
New England
March, 2007
Regional Report

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Rugosa roses respond to hard pruning by delivering you loads of blossoms.

A Healthy Dose of Dormant Pruning

The annual early spring pruning ritual is upon us, thank goodness. While spring cleaning is more about getting rid of the old, pruning at this time of year is about welcoming the new. It's a signal to our plants -- and to us -- that better days lie ahead. We grab our mud shoes, dust off the pruners, and get reacquainted with our plants again, commune with nature, soak up sun and bird song.

With our late-winter cold and snow, spring growth has not yet begun on many plants so there's still time for maintenance pruning. In fact, it can be injurious to a plant to prune when the tissue is frozen, so waiting until shortly before bud break is easier on all concerned. While precise pruning techniques are the subject of numerous books, a few guidelines here can help get us in the right frame of mind.

Deciduous Trees and Shrubs
While it's obvious that a broken or weak branch needs to be removed, it's harder to make ourselves remove perfectly healthy branches for the future goal of bringing more light and air into the tree canopy. I think most people err on the side of not removing enough wood rather than removing too much. I know I do. But I've had to get more drastic with one of my crab apple trees because in spite of being listed as resistant to scab disease, it looked unsightly every year until a heavy, wet snow broke a couple of large branches and I had to remove a lot of broken wood. The improved air circulation has sure helped curb the disease. The same storm tore some branches from a flowering cherry, which looked quite sparse after clean-up pruning. But the flower show was better the next year, so nature helped embolden me.

Early spring pruning also helps keep large shrubs in bounds, such as my Hydrangea paniculata 'Pink Diamond'. It appears to want to take over the front of the garage, but it stays a more manageable 6 feet high if I cut it back drastically every year or two. This promotes lots of new growth, which means a better flower show since it flowers in summer on new growth. Other flowering shrubs that can be pruned in early spring include any that bloom on new wood, such as beautyberry (Callicarpa japonica), rose of Sharon (Hibiscus syriacus), spirea, viburnum, and butterfly bush.

I used to prune my butterfly bushes in the fall and thought they just weren't winter hardy when they didn't return in spring. But they need the stored carbohydrates in their stems to better withstand cold temperatures. That's why, in general, fall pruning isn't recommended in our region. Plants need to carbo load for the winter, too!

While early spring is also a good time to rejuvenate an overgrown lilac by cutting it nearly to the ground (they respond quite well to this), you will, of course, sacrifice the blossoms because they grow from previous years' branches. But the improved flower display in years to come will make up for it.

Shrubby Perennials
Just like butterfly bushes, shrubby perennials -- sometimes called sub-shrubs -- are likely to die over the winter if they are cut back in fall. Russian sage, caryopteris, sage, and lavender are in this category. In late winter or spring, however, they can be cut back by half.

If you just need to encourage a bushier shape on any needle-bearing evergreens, pinching the new growth -- the candles -- later in the spring will do the trick. But if a branch has been damaged, prune it back to a crotch now so new growth will cover the cut.

Broad-leaved evergreens like azaleas, rhododendrons, holly, and boxwood are best pruned after flowering when they are in active growth. But you can cut away any winter damage now.

Roses need even more air circulation than crab apples to reduce conditions that invite disease. That means pruning. I'd rather not tangle with rose thorns at any time of year, but at least in early spring you can see where the thorns are. There's always some winter damage and some branches heading into the center of the bush that have begun rubbing. And some old canes that need to be cut back to the ground to allow new healthy ones to grow, all for the sake of new flowers. This is all I do for most of the shrub roses.

My rugosa roses can handle being cut back drastically every spring, almost to the ground, and without this treatment they would become unmanageable, with long canes stealing their way over the entire garden bed.

Climbing roses benefit from a little more effort. Since they produce flowers on the short side branches that grow from canes that are two or three years old, shortening the side branches will increase the potential for flowers. Also, remove a couple of the older, darker canes each year and tie new ones to the support.

Ramblers bloom best on year-old canes, so each spring you can remove the canes that have previously flowered to encourage new ones.

Hybrid tea roses and floribundas need even more yearly pruning to keep them in top flowering form. These are the roses that tend to be grafted, so there will usually be some suckers growing below the graft that are best yanked off rather than cut, if possible. The blossoms form on shoots growing on year-old canes, so remove older canes, leaving up to six younger canes. Then cut these young canes back to about 12 to 18 inches high.

With any luck you'll be amply rewarded for your efforts. And you'll have generated a list of "To-Dos" while you were looking everything over that will get you out in the garden again as soon as possible. Ahh, springtime!

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