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Gardeners, Be Aware — Popular Species Among List of Invasive Plants to Come Off Market

Jennifer Mitchell
Maine Public
Melissa Higgins of Sprague's Nursery in Bangor

Time is running out for nearly three dozen popular garden plants in Maine, and it’s not because another snowstorm is on the way. It’s because the state of Maine has been warning homeowners about invasive species for several years, and after next year they’ll no longer be allowed for sale or planting.

The list covers popular tree types such as the Crimson King and the Royal Red Maple.

“People want that particular maple. That’s the one with the red leaves. It’s red all year round. They like it because of that color. It’s different,” says Melissa Higgins, a garden expert at Sprague’s Nursery in Bangor.

But Higgins this is the last year those kinds of trees, both varieties of Norway maple, will be available. Starting next year they will be banned, along with 32 other plants and trees.

Higgins says she wasn’t surprised to see Purple Loosestrife on the list, but a few species on the list were unexpected.

“I was surprised about privet, because it doesn’t really grow that well up here anyway. I mean it does grow here, but,” she says, “Probably yeah, more Portland area, so I don’t typically think of it up here. Yellow iris — I was surprised about that.”

A popular and pretty garden flower, according to the state Department of Agriculture, Conservation and Forestry, the yellow iris has been found colonizing Maine’s marshland. And Higgins says one of the biggest disappointments for her customers will likely be the loss of the showy, red Euonymus alatus, commonly known as burning bush, selected for its hardiness and brilliant red fall foliage.

So what’s the problem with the plants identified on the list? Maine naturalist Bob Bittenbender has been waging war on invasive species for years. He says each one just doesn’t fit well into the landscape as we know it.

Take the very popular Norway maple, the first type of which was introduced to North America way back in the 1790s.

“But it is so aggressive as a grower, it is so heavy as a plant that it stops sunlight from getting down. Its roots are shallow and so dense, it forces other plants out, but really the main problem with it is it’s reducing the amount of usable habitat for our native species,” he says.

For example, Bittenbender says certain insects won’t eat its leaves and that means fewer insect meals for native birds.

State regulators are the first to admit that the end goal surrounding non-native species is unclear, and the process is not perfect.

To remove all species that are non-native would mean yanking out about a third of all the plants in Maine, as well as banishing some animals we’ve come to love, such as honeybees and the gardener’s best friend, the common earthworm - both of which were brought here from Europe.

Rather than trying to put things back the way they were at the end of the last Ice Age, State Horticulturalist Gary Fish says the idea is to predict what species might have a lasting and negative effect on the systems that are working well together at the moment.

“It’s really tough to make these decisions, but there are certain plants — and we have a very broad group of professionals that have looked at these plants to see if they’re ones that really are going to cause ecological problems. And we’ve narrowed it down to the 33 plants that we think are those ones that will cause problems in Maine or that are already causing problems in Maine,” he says.

So, back to the Norway maple. Nothing grows particularly well under it — even grass can be reluctant to take root. And because it’s an aggressive, fast grower, it has a tendency to push out Maine’s prized sugar maples, upon which the state’s maple syrup industry relies. And when young, it’s almost indistinguishable from other maple species, making identification and eradication complicated. For those reasons, it’s on the list.

But it’s still very popular. That means that nurseries like Sprague’s in Bangor, which need to make the bulk of their yearly income in just a few short weeks, have a moral dilemma.

“I think we’ve decided to kind of tell people, and just make them aware, which we’ve been pretty good about that anyway, ‘This is going to be your last chance to buy this particlar plant because it is going on an invasive list.’ People may then say ‘Oh! Well I didn’t even know it was invasive, why and what can I learn about it, what are my alternatives?’” Higgins says.

She says while the nursery will likely continue to offer some of the more popular soon-to-be-banned species this year, they’re toying with the idea of having a “Plant This, Not That” display, encouraging people to choose native red maple over the Norway. Or for fall foliage, blueberries and dwarf lilac instead of burning bush.

Retailers have until Dec. 31 to get rid of all remaining invasive plant stock. After that, the selling, distribution or transport of the plants on the list, as well as the intentional propagation, becomes illegal.

At the moment, the state is only planning to ban the sale and transport of the 33 listed plants. There is no mandate to dig up or destroy plants you possess at the end of the year, but they warn that could change in the future.