Invasive Plants

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Host) Everyone loves the different wildlflowers that are blooming along roadsides this time of year, but commentary Charlie Nardozzi says that not all of them are harmless natives.

(Nardozzi) Gardeners love exotic varieties of plants. However, exotic plants aren’t always the friendliest garden companions. Some introductions over the years have turned into monsters, escaping into the wild and wrecking havoc on natural ecosystems. To control their spread, in 2003, the State of Vermont passed a Noxious Weed Quarantine Rule to ban the sale of invasive plants in the state.

The most widely known invasive is purple loosestrife. This is an attractive purple spiked perennial flower that’s in bloom now. It has escaped from garden cultivation and is now found in wetlands and pastures across the state. Plants spread quickly by producing millions of seeds each summer that are disseminated by wind, birds, and water. Although some nurseries claim to have sterile varieties of purple loosestrife, it’s best to avoid this perennial altogether. Try growing summer blooming alternatives such as bee balm, purple coneflower, and Joe Pye weed.

Honeysuckles are a great landscape plant. They provide colorful flowers in early summer and attractive berries, that birds love, in summer and fall. However, some honeysuckles, such as the bush Tartarian and Amur honeysuckle and the climbing Japanese honeysuckle, have become invasive. Birds have spread the seed so readily that now honeysuckles are found crowding out native plants in landscapes and forests. You don’t have to forego planting all honeysuckles though. It’s a matter of choosing the right ones. Trumpet honeysuckle is a good alternative to the Japanese climbing honeysuckle. Arrowwood viburnum and Winterberry holly are good replacements for the bush honeysuckles.

Finally, Asian gardens are becoming very popular. One of the backbones to an Oriental garden is bamboo. However, you don’t want to plant the type of bamboo that is overrunning landscapes in Vermont. The Mexican bamboo isn’t technically a bamboo at all, but grows like one. It’s more commonly called Japanese Knotweed. It grows 8 to 12 feet tall with large, egg-shaped leaves, and bamboo-like stems. It spreads like wildfire by underground rhizomes, overtaking any perennials in is wake. To get an Oriental effect while
avoiding the Japanese knotweed, try growing elderberries, red twig dogwoods, or some of the more exotic bush willows.

The Vermont invasive plant list is available through the state Department of Agriculture. There are other very common shrubs such as burning bush, Norway maple, and multiflora rose, that aren’t on the list, but are a major concern throughout New England. Before planning a new landscape or renovating an old one, do a little research to avoid using these aggressive plants.

The best control for established invasive plants is to pull them out. Be patient. They are called invasives for a reason and often you’ll need to be diligent about removing plants annually. And next time you try an exotic plant in your garden, keep a close eye out for where it pops up next year.

This is Charlie Nardozzi in Shelburne.

Charlie Nardozzi is an all-around gardening expert with a special fondness for tomatoes and roses.

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