Harpswell Invasive Plant Partnership

HIPP volunteers tackle invasive plants at Johnson Field Preserve at Mackerel Cove (Becky Gallery photo)

About the Harpswell Invasive Plant Partnership

The Harpswell Invasive Plant Partnership (HIPP) is a volunteer effort to respond to the explosion of invasive plants on our public lands. The partnership was formed in 2014 as a cooperative effort of the Harpswell Heritage Land Trust (HHLT), the Harpswell Town Lands Committee, the Harpswell Conservation Commission, the Harpswell Recreation Committee, the Mitchell Field Committee, the Harpswell Garden Club, and residents.

What are invasive plants and why are they so aggressive?

The Maine Natural Areas Program defines invasive plants as those “that are not native to a particular ecosystem, whose introduction does or is likely to cause economic or environmental harm or harm to human health.” They can reduce the diversity of native plants by competing for critical resources like sunlight, water, nutrients, and space. They succeed through vigorous growth, prolific reproduction, and other means. The pests that keep them in check in their native country are not usually present here. And along with a change in plant communities comes a web of impacts on other organisms.

This map shows the sites where HIPP is currently focusing its energy.

What is HIPP doing?

Our aim is to create a broad awareness in Harpswell about invasive plants and the problems they create, and to provide information to help residents eradicate or contain them. As a start, in 2015, HIPP volunteers surveyed three HHLT preserves and three town properties: Johnson Field Preserve, the Mackerel Cove Lot, McIntosh Lot Preserve, Giant’s Stairs, Houghton Graves Park, and Mitchell Field. In addition, HIPP surveyed the rights-of-way of 28 miles of Harpswell’s major roads. Our findings were loaded into the iMap Invasives database maintained by the Maine Natural Areas Program.

Using this data, HIPP began a program of invasive removals and site monitoring. We are developing plans for work on other public-access sites. We offer education and training programs for Harpswell residents who want to learn how to identify and remove invasive plants on their own properties, or help our work on HHLT and Town properties.

At this point HIPP is focusing on at least 16 invasive plants that were seen in Harpswell in our initial survey. We realize there are other invasive species here too. For a list of the invasive plants we found in our survey, click here.

HIPP’s approach to controlling invasives

Harpswell is situated on a narrow peninsula and islands, so the potential for contaminating the ocean or our restricted fresh water supply is great. We work to control invasives without further damaging water, soil, desirable plants, and people. We try to avoid using herbicides whenever possible.

The most successful approaches to limiting the spread of invasives are to not plant them and to eliminate them as soon as they appear. HIPP doesn’t have the resources to eliminate all the invasive plants in Harpswell so it is important to prioritize our attack. Controlling a patch of invasive plants takes careful planning and can require repeated treatments over many years. “Best practices” should always be used to ensure success and to avoid environmental impacts. Often more than one method of control may be needed depending upon the species present, the extent of the invasion, and the workforce available. At HIPP we start with non-chemical methods, such as repeated pulling or mowing of invasive plants. When we need to use herbicides, we use the least environmentally damaging formulation and application method practical (such as carefully painting an herbicide onto the cut stem of a large vine, invasive shrub or a tree).

A HIPP volunteer cuts honeysuckle at Johnson Field Preserve (Becky Gallery photo)

Upcoming Activities

On Monday, July 31, please join the Harpswell Invasive Plant Partnership (HIPP) at a work party to remove invasive plants at Houghton Graves Park. We plan to remove plants such as purple loosestrife, asiatic bittersweet, barberry, autumn olive, and thistle. As these plants are removed, our native plants will have an opportunity to thrive at this beautiful park.

At the event, we will provide a short discussion on identifying and removing invasive plants, then work together on removal. Please bring your own water and, if you have them, work/gardening gloves and weeders/clippers.

Date and time:  Monday, July 31 from 9:00 a.m. to 12:30 p.m.
Location:  Houghton Graves Park, 1714 Harpswell Islands Rd, Orr’s Island
Who:  HIPP volunteers and interested neighbors
What:  Learn, work, and enjoy refreshments
Cost:  Free
RSVP:  RSVP by July 27 by clicking here or by contacting Julia McLeod at outreach@hhltmaine.org or 207.837.9613.

For more information or to contact HIPP

Follow HIPP on Facebook

Sign up for emails from HIPP

Ask a question about an invasive plant or about HIPP

Report new invasive plants in Harpswell that are not already on our list

Request a trained HIPP volunteer to help you identify invasive species on your land and to suggest a possible control plan

Invasive Oriental Bittersweet chokes out native plants at Curtis Farm preserve (Becky Gallery photo)Su

Support HIPP with a donation


HIPP has created fact sheets about identification and control of 16 invasive plants found in Harpswell. Click here to browse the fact sheets.

Read a 2017 article about HIPP and why invasives are a problem (including some interesting information about ticks)

Read an article about disposing of invasive plants in Harpswell

Maine Natural Areas Program Invasive Plants Photo Gallery

Michigan State University’s Best Control Practice Guide to Invasive Plants

Another Michigan State University site for more species

Before you consider using herbicides in Harpswell read the Harpswell ordinance on pesticides

Maine state regulation bans the sale of some invasive plants

For lists of native Maine plants to consider for your property, check out: