GARDENING : A Cutting Remark: Thoughtless Pruning Means Shear Trouble
If you haven’t made a New Year’s resolution yet, consider this one: Don’t take shears to anything in your garden this year without knowing why you’re making the cut.
Pruning without pondering results is butchery, warns Sean Cincotta, a horticulturist for Sherman Gardens in Corona del Mar. With a few thoughtless swipes, you can destroy a plant’s natural grace permanently, he says.
Tree-topping is the most egregious example.
Botched blade work also saps a plant’s strength, makes it more susceptible to diseases and, if continued, can eventually kill it.
But you don’t want to give up pruning entirely. There are perfectly legitimate reasons for performing a little surgery on your plants now and then.
One reason is to encourage the production of flowers or fruit. Some plants only produce on new wood. With these plants you get a better crop by trimming back every year to encourage new growth. Wisteria and peach trees are good examples. If you don’t trim a peach tree’s branches annually, each succeeding crop will be produced further out on its branches, putting great stress on them--not to mention making the fruit harder to harvest.
Severe pruning can also rejuvenate an aging plant otherwise headed for the compost heap. The nursery industry has a maxim for this: “Prune weak plants hard, strong plants lightly.”
Ron Bell, head gardener at Sherman Gardens, used this principle to revive two venerable hibiscus bushes which had ceased to flower. Though he normally prunes hibiscus lightly--mostly opening up the interior to bring light into the plant--these two he cut nearly to the ground.
“I added a little low-yield nitrogen to the soil and deep-watered them, and they sprang right back,” says Bell. “It’s like having brand-new plants.”
You can also prune for symmetry--encouraging new growth on the sparse side of a lopsided plant, for instance, or pinching back overly vigorous shoots to make a shrub more orderly.
It’s when gardeners prune to restrict a plant’s growth that most of us go wrong, according to nursery personnel. Not understanding how plants grow, gardeners have a tendency to treat pruning as a haircut: They take a little off the top.
Shearing off the top, however, urges a plant to produce more foliage. Any time you cut a stem just above a growth bud, you’re spurring on the plant to produce a new shoot at that point. Next year there’s twice as much to prune. That’s why topped trees have to be redone so often. Cutting anywhere else than above a growth bud is even worse; it leaves an ugly stub.
A better solution is thinning out a tree or shrub by removing a few carefully selected branches, according to Adam Lambre, green goods buyer at Nurseryland in Mission Viejo. Thinning cuts spread new growth more evenly throughout the plant by channeling the new growth into existing branches. Taking a little off the top, in contrast, creates a host of vigorous new shoots growing straight up from the plant’s crown--an ugly effect plant people call a “witch’s broom.”
Your first move, Lambre says, should be removing all dead wood. Then cut out any branches that rub together, cross or grow toward the interior of the plant rather than to the outside. If a shrub or tree has been neglected or badly pruned for many years, taking out all the offending branches at once might leave it too bare. In this situation, take out only the “worst-case” branches this year, and clean up further in succeeding years. With any thinning cuts, cut back branches to where they join a larger branch or stem.
Now step back and assess your work. You may be finished. Though the thinned-out shrub may not be any shorter than before, it will look smaller because it is less bulky.
It will also be healthier. Thinned-out plants get more air and light--essential ingredients for plant health--and thrive, Lambre says.
Finally, examine the buds on the remaining branches. If you cut above any of these buds--a pruning technique called heading back--you’re diverting growth to that point. Is this where you want it?
Make sure you’ve selected an outside bud for any heading-back cuts so growth will be directed away from the center of the plant. And prune just above the bud and sloping away from it at 45% angle so that water won’t collect at the cut.
When to prune? Since the likelihood of frost damage is minimal in Southern California, you can prune plants almost any time without doing harm. You might be severing next spring’s florescence, though.
All flowering plants bloom from either new growth or old wood. Generally speaking, spring-blooming shrubs produce flowers on last year’s wood. If you prune them during winter, you’re cutting away stems that are getting ready to produce flowers. Wait until after the plant has stopped blooming.
The blooms on summer and fall-flowering shrubs, on the other hand, generally appear on new wood. If you prune these shrubs in the spring, you’ll be sacrificing flowers. Prune in the winter.
A good reference such as “Sunset Western Garden Book” will tell you which category your plants fit into and when to prune.
Cincotta demonstrated how to put good pruning principles to practice by grooming one of Sherman Gardens’ hybrid tea roses. Since hybrid teas are cut back sharply, you might think rose pruning consists of heading back. But good rose pruning, he insists, like most pruning, consists primarily of thinning cuts.
Roses need lots of light and air circulation, Cincotta says. This is why, he says, you ideally want only between three and five canes on a hybrid tea bush, and never more than six. If you have more, thin out, removing canes from the base of the plant. Best candidates to do away with are the oldest, woodiest canes, because they are the least productive, and the weakest, most spindly ones, because they never will be. Also thin out branches that cross or grow toward the interior.
Head back all remaining canes by one-half to two-thirds (Cincotta recommends the former) but not so far back as to cut into old wood. Hybrid teas are repeat bloomers, beginning their performance in early spring on new wood. That’s why now, their most dormant time, is the best time to prune.
If exposed cut surfaces are bigger than a dime, says Cincotta, they should be sealed. He uses Elmer’s Glue; it’s cheap, easy to apply and aesthetic because it’s invisible.
Inspect your pruning arsenal before you do any pruning this year. The sharper the blade, the cleaner the cut. The cleaner the cut, the quicker your plant recovers.
Pruning shears should be professionally sharpened on a regular basis just like kitchen knives, Lambre says. Shears should also be cleaned on a regular basis with a disinfectant, he says. A 10% solution of Chlorox works well. So does kerosene.
Clean every time you’ve pruned a plant that might be diseased, Cincotta suggests. “I always disinfect after pruning roses; they’ve always got something.”
Oil the blades regularly with WD 40, too, he says.
If you’re using anvil-type shears, you might also consider switching to a hook-and-blade type, which cut more like a scissors. “Anvil shears crush the wood instead of cutting it cleanly,” says Cincotta. “Plants don’t heal as fast. I don’t like them at all.” Watching someone like Cincotta, Lambre, or Bell at work might change your whole attitude about pruning. You might, like Bell, even come to think of it as the most rewarding part of gardening.
Good pruning, he says, isn’t subduing nature; it’s cooperating with it to enhance a plant’s natural beauty. “All most plants need is a little definition so you can appreciate the structure of their branches,” Bell says. “After all, there’s more to plants than flowers.”
Observing an expert at work is the best, and quickest, way to learn about pruning.
* Horticulturist Cincotta will be grooming the remainder of the Sherman Gardens’ hybrid teas today, 9:30 a.m. to 11 a.m. 2647 E. Coast Highway, Corona del Mar. Free.
* The Orange County Rose Society will be pruning the City of Westminster’s roses today and Sunday, 1 p.m. at the Civic Center, 8200 Westminster Blvd. Free.
* Rose-pruning demonstrations conducted Jan. 11 and 18 at 11 a.m. by Cristin Fusano at Roger’s Gardens, 2301 San Joaquin Hills Road, Corona del Mar. Free.
Take advantage of this slow period in the garden to do a little self-educating. “Sunset Western Garden Book” contains an excellent overview on pruning. For more details regarding specific plants, “Sunset Pruning Handbook,” an inexpensive paperback, is also good. Another manual recommended by several nurserymen is “How to Prune Almost Everything” by John Philip Baumgardt, available at most libraries.
Plant Amnesty will send you its brochure “Guide to Pruning” for the price of a self-addressed, stamped envelope. Write to 906 N.W. 87th, Seattle, Wash. 98117. If you have a shrub in your yard sheared into what Plant Amnesty founder Cass Turnbull calls a “green meatball” that you’d like to convert to a more natural shape, enclose $1 and request a reprint of her article “Unshearing Shrubs.”
