When you need a concrete bunker to contain a plant, you know you’re in trouble. Some varieties of bamboo are so determined to spread that only extreme measures, such as plastic or concrete root barriers, can keep its rhizomes from running from here to kingdom come. Running varieties include Chimono-bambusa, Indocalamus, Pleioblastus, and Sasa. Clumping varieties are much better behaved — Bambusa, Borinda, Chusquera, Fargesia, and Otatea grow and spread more slowly.
English Ivy (Hedera helix)
This popular ground cover and fence-grower has overstayed its welcome. Imported from Europe, where it adorns old buildings with charming effect, English ivy has overwhelmed American parks, forests, and suburban homes, climbing any kind of siding and drowning trees. It’s listed as a noxious weed in the Pacific Northwest and an invasive species along the Eastern seaboard. Pull it up in spring before new shoots can spread.
This ruthless invader will swarm over trees, buildings, road signs — anything in its path. It’s a semi-woody vine that can grow 1 foot per day, spreading through runners, rhizomes, and seeds. Once the plant takes hold, there’s no stopping it. Well, herbicides can stop it if you apply them for years. And herds of kudzu-grazing goats will eventually destroy the plant. If you don’t keep goats, spray and mow kudzu until it gives up.
Japanese Stiltgrass (Microstegium vimineum)
This east Asia import creates a thick mat that starves native plants in forests and wetlands; your garden beauties don’t have a chance. Japanese stiltgrass, a summer annual, spreads above ground through rhizomes and seeds that love to grow in loose soil. So the more you rip and dig out the plant, the better it’ll grow in the disturbed and vacant space. This weed is best controlled with pre-emergent herbicides applied in late spring or early summer.
Purple Loosestrife (Lythrum salicaria)
Although this wetland perennial was once used to treat dysentery, it can quickly form impenetrable stands that starve out native vegetation and wildlife. No wonder it’s nicknamed Beautiful Killer and Marsh Monster. The best way to control it may be with natural enemies: Certain kinds of leaf beetles and weevils have been used to stop infestations. If the plant invades your garden: Dig it out, burn debris, or tie it in a dark plastic bag to prevent it from spreading in landfills.
OK, a clip of mint gives iced tea some punch. But you’ll pay a big price if you plant this edible. It’s relentless, spreading through runners in any moist and partially shaded area. Mint laughs in the face of buried pots and tubs, and quickly spreads beyond those borders. Only grow it in a container on your deck or indoors on a sunny windowsill.
Chinese Wisteria (Wisteria sinensis)
Yes, it’s beautiful. But this python-like plant can twist around a tree so tightly it can kill it. The stout stalks of Chinese wisteria — and its cousin, Japanese wisteria (Wisteria foribunda) — can grow to more than a foot in diameter, forming a thicket that can smother other plants and collapse arbors. Nineteen states list wisteria as invasive. Yank it from trees, arbors, and pergolas, then spray with a systemic herbicide.
Trumpet Vine (Campsis radicans)
The orangish flowers of this vine (aka trumpet creeper) are butterfly magnets. But it’s a relentless grower, grabbing onto your house or any nearby tree — good luck pulling it out of your garden. The more you cut or dig it, the angrier it gets, sending shoots far away from the main plant just for spite. Persistence is the best way to foil trumpet vines. Use a sharp shovel to dig up the mother plant and shoots, and clean up any spent blooms so the plant doesn’t reseed.
Leafy Spurge (Euphorbia esula)
This three-foot-tall invader not only crowds out other species, but it spreads toxins that prevent native species from growing near it. Leafy spurge seeds explode from capsules and can live in soil for seven years, making control a Sisyphean task. If you find them in your yard, spray plants (year after year) with a systemic herbicide.