With the purple loosestrife in full bloom right now, this is the best time to find and remove this invasive plant – before it sets seed.
WHAT IS PURPLE LOOSESTRIFE?
Purple Loosestrife is a very hardy, highly invasive non-native perennial plant. It grows upright, 3 to 10 feet tall. It produces bright purple flower spikes in July through September. Its leaves are long and narrow sightly shiny, with smooth edges (not toothed) and distinctive vein pattern. The leaves usually occur in pairs along the square, slightly fuzzy stem although there can be groups of 3 leaves around the stem. Young pants may be a lighter shade of green and may not bloom the first year.
WHY IS PURPLE LOOSESTRIFE A PROBLEM?
As beautiful as this plant is, its beauty is deceptive. It is altering and degrading our wetlands, lakes and streams.
Native to parts of Europe and Asia, purple loosestrife was originally brought to the US in the 1800’s for ornamental use but it quickly escaped from the gardens where it was planted. While it prefers wetland, it has also adapted very well to drier sites and can be seen growing along roadsides and hillsides too. Purple loosestrife reproduces through underground shoots as well as seeds. A mature plant can produce over 2 million seeds each season and it can quickly take over large expanses of land if not kept in check. Because it is not native here, we have no diseases or insects that would naturally help control its spread, although researchers are exploring the possibility of introducing insects from the areas in Europe and Asia where purple loosestrife is native.
WHAT IS THE THREAT TO ROARING BROOK LAKE?
Healthy wetlands, including the lake, shoreline, streams and inland wetlands, are biologically diverse. Hundreds of species of plants, fish, insects, birds, mammals, reptiles and amphibians rely on healthy wetland habitat for food, shelter and nesting ground. When purple loosestrife invades, it reproduces and grows aggressively in the marginal areas of the lake, along the shoreline, in crevices in lake walls and rock outcroppings and along our streams. It out-competes the native plants that are important for the health of the ecosystem. In displacing the naturally-occurring plants, it eliminates food, nesting area and shelter for wildlife and reduces the site to a field of a single kind of plant (a “monoculture”) that none of our wildlife can use. Purple loosestrife can also block streams and interfere with the natural water flow and fill in shallow areas of the lake, limiting recreational use.
WHAT CAN WE DO TO STOP THE INVASION?
Now is the best time to spot purple loosestrife and remove it — before it has gone to seed. The best approach is to remove the plants, roots and all, but with large plants, this is not always possible as the roots are deep. An alternative is to cut the plant down to the ground to prevent the seeds from setting. If it has already begin to set seed, the plant should be cut down over a plastic bag so that any seeds that may shake loose fall into the bag, not on the ground. If the roots are left in the ground, the plant will regrow in future years, but if it is cut down several times throughout the following summers it will eventually lose much of its vigor and may die on its own. The plants and stems that are removed should be put in a black plastic bag and be allowed to rot for a few months. If the fresh plants or parts of plants are dumped in the woods or in a compost pile they will most likely regrow.
NATIVE ALTERNATIVES TO PURPLE LOOSESTRIFE
If you have purple loosestrife growing in your yard and hate to see it go, here are some good options to replace it with. These are all mid- to late-summer blooming native plants that will provide important food for birds, butterflies and bees as they prepare for their fall migration and over-wintering. They are all available at nurseries and garden centers in a variety of cultivated colors and sizes.