Gardenwise: Sucker Punch Unwanted Growth

This maple tree is exhibiting typical water sprout growth — thin vertical shoots reach for the sky.
This maple tree is exhibiting typical water sprout growth — thin vertical shoots reach for the sky.

By Susan Tito

In my garden, it seems like there’s a sucker born every minute.

Forgive me for taking liberties with the phrase P.T. Barnum is credited with coining. For the record, the sucker the master showman referred to was of the gullible human variety while the kind I’m drawing attention to is strictly of botanical origin.

Even if you think you don’t know what a plant sucker is, chances are you’ve seen one or two in your travels. A sucker is robust vertical growth arising from a plant’s roots or its lower main stem. In some cases, the growth doesn’t resemble anything else on the plant.

In trees, suckers often occur in ornamental or fruiting varieties that have been grafted. In extreme cases, a suckering specimen can resemble a tree on top and a shrub at its base. Sometimes it can look like two different trees freakily fused into one. That’s because it is two trees (the rootstock being selected for size or disease resistance and the top typically prized for ornamental value).

Overfertilization, drought, storm damage and excess moisture — any unusual extreme condition — can lead to suckering, but much of the time it comes down to genetics. Some plant species, including lilacs, roses, crabapple and dogwood trees — even tomato plants — are notorious for suckering.

In fact, “some trees and shrubs sucker as part of their normal habit — think forsythia and certain types of brambles that form thickets,” said Sandra Vultaggio, a horticulture consultant at Cornell Cooperative Extension in Riverhead.

A rugosa rose sucker has popped up several feet away from the host plant, located on the other side of the fence.
A rugosa rose sucker has popped up several feet away from the host plant, located on the other side of the fence.

I have a forsythia and find it to be fairly well behaved, especially compared with the horror show going on in my backyard right now. 

For years, as part of my annual garden maintenance, I routinely cut back suckers on two honey locust trees and one Bradford pear next to my deck. I skipped that chore last year, choosing to focus on another problem area elsewhere on my property. This year I’m paying the price with suckers that are nearly 4 feet tall!

In addition to suckers’ giving your garden an untidy appearance, there’s an important reason you’ll want to remove them (hint: It has something to do with the name).

This unwanted growth can “suck away” a plant’s energy. Suckers can penetrate into the soil and generate multiple roots, weakening the original plant.

Suckers aren’t the only kind of undesirable growth wreaking havoc in the garden. Keep an eye out for water sprouts, fast-growing upright shoots that often arise from a tree’s trunk or branches. If you’re unlucky like me, you’ll have both suckers and water sprouts on the same tree!

“Water sprouts most often occur when there is damage to a branch in the form of severe breakage, hard pruning or even pruning at the wrong time of year,” said Ms. Vultaggio. “Water sprouts usually ‘sprout up’ from latent buds. Both water sprouts and suckers, when forming in response to damage, tend to produce weak, very fast-growing wood.”

A Bradford pear tree sucker (shown in foreground) grew several feet in only one year. It is surrounded by shorter suckers — all of which require removal.
A Bradford pear tree sucker (shown in foreground) grew several feet in only one year. It is surrounded by shorter suckers — all of which require removal.

Ironically, sometimes the more you prune away suckers and water sprouts, the more you generate! However, that doesn’t mean that you should ditch your pruners and give up. The key is not to overdo it. If you delay pruning out suckers and water sprouts, they will harden and grow, making future removal that much more difficult.

Say “so long, suckers!” with the following tips:

• Prevent suckers and water sprouts by maintaining good plant health. Don’t overfertilize or allow plants to become stressed during dry periods.

• Don’t overprune shrubs and trees. Specifically, practice the One-Third Rule of pruning, removing no more than one-third of wood per year. Any more than that and you could trigger a survival response that prompts the plant to generate more suckers and water sprouts.

• Prune at the correct time of the year (late winter for summer bloomers; after flowers fade for spring bloomers). Refrain from fall pruning, as that stimulates growth at a time when plants are about to go dormant.

• Refine your pruning technique.  Use sharp, clean shears or loppers to cut water sprouts back to the trunk, leaving the branch collar.

• For suckers that crop up in the lawn, continually cut them down — better yet, mow them.

“The more you deprive them of sunlight, the weaker they will become,” said Ms. Vultaggio.

Prevention seems to be the best strategy for dealing with suckers and water sprouts. But if, despite your best efforts, you still get a few, take out your trusty pruners or loppers and do what W.C. Fields would advise: Never give a sucker an even break.


Susan Tito
Susan Tito

Susan Tito is a freelance writer and proprietor of Summerland Garden Design & Consulting (summerlandgardendesign.com). She earned a certificate in ornamental garden design from the New York Botanical Garden and is a member of the American Horticultural Society and Garden Writers Association. She can be reached at stito630@gmail.com.

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