Tackling invasive plants: Where to start, what to do and why to do it

Spring is almost upon us and leaves are popping out. Those early bits of green on shrubs and bushes likely appear on plants you don’t want in your garden, like Japanese barberry and shrub honeysuckles. Both leaf out early in the spring, which makes them easy to locate.

Invasive plants are more than just weeds — they are plants not native to this region that can harm the environment, human health and the local economy. Because these species are new, native plant eaters usually don’t eat them, which gives them a competitive advantage.

Loss of our native plants causes significant problems for native wildlife. Japanese barberry and shrub honeysuckles create excellent habitat for disease-carrying ticks. There are plenty of reasons to tackle invasives on your property.

First you have to find them. A number of excellent resources are available to help identify invasives. Check out maine.gov/dacf/mnap for useful knowledge and information about how to order the Maine Invasive Plants Field Guide. The Harpswell Invasive Plant Partnership will help you identify invasive plants on your property and suggest control methods. See hippmaine.org.

Once identified, how can invasive plants be removed safely? A number of factors must be considered in designing a strategy to control the spread of invasive plants. First, is the target plant within 25 feet of the maximum high-tide mark for a body of water? Town ordinances on pesticides prohibit the application of fertilizers and pesticides within this 25-foot zone.

The area within 75 feet of the high-tide line or upland from a stream or pond is the buffer zone, which we want to conserve. Within the buffer zone, the town’s guidelines require that vegetation under 3 feet in height and other groundcover be maintained. There are also guidelines for removing larger trees and shrubs.

Trees, shrubs and grasses all play a critical role in ensuring that stormwater and snowmelt seeps into the ground rather than running rapidly off into our nearby waters. We want our underground reservoirs replenished and our marine resources protected. No one wants their well to run dry!

Harpswell’s rules protecting the buffer zone define the strategies that can be used to manage invasives. Within the buffer zone, use mechanical means like cutting or digging to tackle invasives. Outside the buffer zone, cautious use of herbicides can be used to tackle infestations too large or dense to remove mechanically. The use of chemicals is regulated by the Maine Board of Pesticides Control and town ordinances — these rules must be followed!

Improper or excessive use of herbicides can cause considerable damage to plants, insects and aquatic life. Get expert help! Our Codes Enforcement Office works to uphold the standards set by our town’s ordinances and state regulations to maintain the natural beauty of Harpswell. Contact this office before any tree removal in the Shoreland Zone and for other questions you may have about working along the shores of Casco Bay.

Once you’ve removed the invasives, consider what to put in their place. Often native plants will fill in cleared areas, given the opportunity. There are also many beautiful, beneficial native plants available to replant cleared areas — and a host of resources to help you decide which plants best fit your environment. Check out the Wild Seed Project, as well as the University of Maine Cooperative Extension for Plants for the Maine Landscape and Native Plants: A Maine Source List. Links to these sites are on HIPP’s website.

Maintaining the beauty of Harpswell, reducing invasive plant growth and encouraging native plants are goals shared by the Harpswell Invasive Plant Partnership, our town’s Conservation Commission, and the Harpswell Heritage Land Trust. All of us living here have a vital role to play in preserving that beauty and ensuring a healthy habitat for wildlife and ourselves.