Grantham to host invasive species workshop June 17 at Town Hall

Japanese knotweed, oriental bittersweet and glossy buckthorn can turn a Grantham yard, shoreline or trail edge into a long cleanup job, and the town is putting that problem front and center with a workshop on June 17 at Town Hall.

The Grantham Conservation Commission has scheduled a talk on invasive species for Wednesday, June 17, 2026, from 9 a.m. to 12 p.m. at Grantham Town Hall, 300 Route 10 South. The town calendar identifies the program as a Grantham Conservation Commission talk with UNH Forester Mike Gagnon.

The timing matters for landowners and shoreline residents headed into the growing season, when fast-spreading plants can fill in field edges, choke garden beds, and creep into wooded lots before cleanup gets harder and more expensive. Grantham’s Conservation Commission says its mission is to foster the proper utilization and protection of the town’s natural resources while encouraging appreciation by current and future residents and visitors, and the workshop fits that charge by treating invasive growth as a practical maintenance issue as much as an environmental one.

UNH Cooperative Extension says invasive plants can reduce biodiversity, imperil rare species, reduce wildlife habitat, degrade water quality, reduce forest production and cause human health problems. Its New Hampshire invasive plant materials list common species including glossy buckthorn, European barberry, Japanese honeysuckle, purple loosestrife, autumn olive, swallow-wort, Japanese knotweed, oriental bittersweet, multiflora rose and Japanese barberry, all of which can be useful for residents trying to identify what is taking hold on their property before it spreads farther.

The state response is not just educational. New Hampshire law prohibits collecting, transporting, selling, distributing, propagating or transplanting listed prohibited invasive plant species. Along the shoreline, the stakes are higher still: the Shoreland Water Quality Protection Act and related rules regulate vegetation removal, excavation, fill and development within protected shorelands near public waters to protect property, water quality, human health, flora and fauna, and recreational opportunities.

New Hampshire has also battled aquatic invasive species for years, and the Department of Environmental Services says many lakes and rivers now have infestations. That puts a local workshop in Grantham into a wider state effort built around prevention, early detection and proper disposal, a reminder that a few seedlings ignored in a yard or along the water can become a larger and more costly problem across Sullivan County.