The ultimate size of a tree or shrub that’s listed in catalogs and on plant labels isn’t actually the largest size that plant can grow. It really is just the size you should use when designing and/or, for those who don’t design, planting a landscape.

Two weeks ago, I wrote that a bird’s nest spruce, listed with an ultimate height of 3 feet, had reached 6 feet in my garden. My editor was shocked. She wondered if the plant developers were trying to deceive buyers, and more than that, given that “ultimate” means “maximum,” felt that the “ultimate height” should represent its limit. After all, words have meanings so that we can all understand one another.

But that’s not what it means here.

Betty Ann Listowich, president and co-owner of Norpine Landscape in Kingfield, and Chad Skillin, head of the design division of Skillins Greenhouses, agreed that “ultimate” in this case actually means how the plant will look after about 10 years. It is the ideal size for the plant, and when it will look at its best.

For many landscapes, 10 years is ideal.

According to the National Association of Realtors, the average time a person lives in a house he or she has purchased is 13 years – and that is up three years since 2008, when the real-estate market collapsed and buying a house became more difficult.

I’m not sure if the plant breeders knew that figure when they came up with their ultimate height guidelines, but it makes sense: Plant the landscape when you move in, enjoy it for 10 to 13 years, sell the house when it looks perfect and leave the problem of the too-large plants to the new owners.

But some people – including my wife Nancy and me – do stay in the same house for longer periods, sometimes their entire adult lives or even multiple generations. For such people, plants that grow too large can be a problem. Fortunately, it’s a problem that can be handled.

“I very often will get called into a landscape where plants have been in for 30 or 40 years, and the plants have outlasted their meaning in the landscape,” said Listowich, a past president of the Maine Landscape & Nursery Association.

A bird’s nest spruce, the shrub that ignited the linguistic (and truth-in-advertising) debate. Stephen VanHorn/shutterstock

While pruning may be possible, the result can be ugly. She mentioned an attempt by one of her employees to trim a bird’s nest spruce – the very species in our yard that prompted this column. He cut so much off the bottom that the pruned shrub looked like a giant lollipop combined a sore thumb, she said.

“Often the best thing to do is rip it out,” she said.

Skillin mentioned a plant that should definitely be pulled out. “Remember when we could still sell burning bush? The label said 6 by 6 feet,” he said.

Burning bush is now illegal to sell in Maine because it is invasive, but many Maine yards still feature it. It can grow as large as 20 by 20 feet.

For readers dealing with 10-year-old trees and shrubs that are just beginning to get too big, start with some judicious pruning. Ideally, wait until next March when the plants are dormant or, for plants that blossom before mid-June, just after they bloom in the spring, because the buds for spring flowers have already formed.

Don’t just cut the branch tips. Pruning should be considered at least a three-year project, cutting out the tallest and widest branches at or near the tree or shrub’s main trunk or, in some cases like lilacs, at ground level. Keep in mind that the more severely you prune a shrub or tree, the more new growth you will get. Pruning spurs growth.

Listowitch said the best time to think about how large the plant will get is when buying it.

“I always ask people what their patience level is,” she said.

With new landscapes, homeowners often want the property to look finished as soon as they move in. They want the largest plants available, and often want them planted closer together than recommended, so they will fill the space and look finished from the start. Listowitch said it pays to be patient. As I wrote last January, it is healthier for the plants and a lot less expensive to buy them when they are small.

For the years before the trees and shrubs become mature, instead fill empty spaces with perennials like hosta and coneflowers or with annuals, which have the advantage of blooming all summer long. The downside is that frost kills them, so you’ll have to replant every spring.

Norpine has done a lot of work for the Maine Department of Transportation, planting evergreens along highways; Listowich said that convinced the state go with small seedlings, which will catch up with the large ones after five to seven years.

She and her husband recently downsized from an old farmhouse in Kingfield to a newer, smaller place in Freeman Township. They started with small seedlings, supplemented with annuals and perennials.

She is pleased with how the new place looks – and expects to be happy with her gardens for many years.

Tom Atwell is a freelance writer gardening in Cape Elizabeth. He can be contacted at: [email protected]

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