Two Invasive Plants to Look Out for This Summer

By Jeff Stann

Two flowering plants will be appearing in Harpswell this summer that bear watching. Both are invasive, crowding out native plants and taking over gardens and wetlands. Both can be controlled relatively easily if we get to them as soon as they appear.

The first is Purple Loosestrife (Lythrum salicaria), a perennial found along roadsides and disturbed wetlands. Growing 2 to 6 feet tall, it is most easily identified by its spikes of magenta-colored (sometimes light pink) flowers. Loosestrife begins to bloom in July, then re-blooms in August and in September. A single plant can be dug up; but if you have quite a few, it’s easier to cut off the flowers and bag them. This will exhaust the plants’ vitality in a few years. New plants will continue to emerge from existing seeds in the soil for a few years, so cut areas should be monitored.

The second is known variously as Himalaya Touch-Me-Not, Ornamental Jewelweed, or Himalaya Balsam (Impatiens glandulifera). This is a coarse annual also found along roadsides, as well as wet meadows, stream sides, and gardens. Growing up to 6 feet tall, it has six-sided thick, hollow, reddish-green stems, and distinctive pink or purple flowers in summer. The best way to control it is simply to pull up the entire plant and bag it. Again, because existing seeds may remain viable in the ground, you should repeat this for two or three years. Himalaya Balsam is listed by the state of Maine as an EDRR (Early Detection/Rapid Response) plant – an invasive plant recently detected in the state that could be eradicated if removed before it spreads more widely. Our two native Jewelweeds – they are smaller and have orange and yellow flowers – will fare better without their bigger Himalayan cousin to bully them.

Invasive plants that are bagged securely should be taken to the town Transfer Center and deposited in the general trash dumpster at the top of the hill. (Remember to weigh in and out when dumping there.) The trash is then placed in a landfill, and the invasives are unable to re-sprout and spread.

The Harpswell Invasive Plant Partnership (HIPP) has fact sheets about Loosestrife, Himalayan Balsam, and other invasive plants. Click here for a list of the fact sheets.

HIPP can help Harpswell residents identify invasive plants on their properties (HIPP-HELP). One of our volunteer experts will walk your land with you pointing out invasive plants and suggesting ways to control them. From the main HIPP webpage, scroll down until you see: “Request a trained volunteer.” Or call Jeff Stann at 373-1811.

July 2017