Plant demons slug it out for survival in your garden

Ha!

Take that, you stinkin' mint. Moneywort wins with a chokehold.

In your garden, one aggressive plant can sometimes win a smackdown with another — and mint and moneywort are two prime examples.

Novice gardeners often are unaware that mint should be kept in a container because it goes everywhere. Once planted, mint spreads by roots and by seeds. Moneywort, a ground cover with leaves that look like small coins, grows in all directions, searching out real estate and destroying anything that gets in its way.

Put them in the same bed if you dare and see what happens.

At some point, most gardeners have planted a huge mistake, sometimes several. Call them the garden demons.

These devil plants have competitive advantages that include resistance to disease, insects and other plant-eating organisms that serve as controls. They often grow and leaf out earlier than plants around them, hogging sunlight, moisture and soil nutrients. They can reproduce from seed and plant parts that remain viable underground for a long time. And they can grow in a variety of soil conditions, from the sliver of soil in the cracks of a sidewalk to the richest loamy garden beds.

Sea oats grass is the bane of Cynthia Zurmuhlen's Bellevue landscape. She planted it on purpose, but now she calls it “a thug.”

“I love the grass. I love the seed heads. But it's so prolific. It will outgrow anything around it.”

Zurmuhlen, a master gardener, said the plant is one of two native grasses she knows will grow in shade. A grass called “bottlebrush” is another, and it's less invasive.

“Sea oats loves shady, moist areas, but it will take up in sun, too,” she said. “I can't believe all the places it's growing. It's adaptable to wet conditions and dry conditions.”

Unfortunately, the seed heads are its crowning glory. If you have to control it by cutting off seeds, what's the point of having the sea oats?

“I've had it for nearly five years, and the past two years, I've really focused on staying ahead of it. I think you could say it's a low-maintenance plant that requires more attention to get rid of it than to keep,” Zurmuhlen said.

No kidding.

In Betty Greiner's garden, a friend dislodged a 12-foot-long root of honey vine milkweed before the root snapped, leaving who knows how much root behind. But that weed wasn't the biggest thug there. That honor goes to the goldenrod.

“I bought it at a nursery,” the Bellevue woman said. “It was the dwarf variety. The first year and the second, it was 18 inches tall. Then it died.”

A year or two later, Greiner had goldenrod everywhere, not the dwarf variety, but the taller goldenrod that grows wild and free on the prairie.

Greiner, a master gardener emeritus for the University of Nebraska Extension in Douglas and Sarpy Counties, said gardeners often gain valuable experience from mistakes like the milkweed and goldenrod, both with “roots that go to China.” Those lessons include what not to plant and what to do to get rid of thugs.

Extension horticulture associate Kathleen Cue said her “oops” plant was labeled “Boltonia.” What came up was a genetic relative with Neanderthal manners.

In the second year, this daisy impostor was everywhere.

“It covered a 5-by-5 foot area,” Cue said. “There was layer upon layer of roots. I dug a good 8 inches down for two solid nights.”

Comfrey was Bob Green's nemesis. The Springfield, Neb., man planted it knowingly. It was an herb with a large purple bloom. And it took over. Now he can't get it out of his iris bed.

Mint, the chocolate variety, was Amy Smith's monster plant.

“It smells wonderful. I hate tearing it up, so it decides to take over wherever it has a mind to,” said Smith, also of Springfield.

Even veggies can play the role of demon. The ‘Sweet One Million' tomato, for instance, does what it wants. If you let a single tomato from this prolific plant fall to the ground, the yield next year will be about a hundred tiny tomato plants, Smith said.

Then there's chameleon.

Also called Houttuynia cordata, like a name out of “The Lion King,” it has colorful leaves and rhizomes underground that break off and resprout when you sever them.

This “sweet-looking flower with the heart-shaped leaf” stinks, said Lisa Swanson, a master gardener who lives in Bellevue.

“It smells like a urinal.”

She said this plant with its pink and green leaves is one of the most aggressive plants she's known.

“I bought it and I battled it,” she said. “It spreads underground. It grew way out into my lawn.”

She dug down deeply with a spade. And still it persisted. She wore rubber gloves and used an herbicide (RoundUp) applied by hand to every stem and leaf. And it's gone.

For now.

Contact the writer:

444-1059, rhonda.stansberry@owh.com