Managing invasive plants is an important part of caring for our landscapes, whether you're maintaining a backyard, forest, or park. Once you've taken the time to remove these plants, it's just as important to dispose of the plant material properly to avoid accidental spread. 

As of July 2016, yard and leaf debris—including material from invasive plant control—is banned from Vermont landfills. The information outlines recommended methods for rendering invasive plant material nonviable and disposing of it responsibly.

Thanks to UNH Extension for sharing this information, originally developed by the Invasive Species Outreach Group—a network of volunteers helping landowners manage invasive plants—with assistance from the Piscataquog Land Conservancy and the NH Invasive Species Committee. Edited by Karen Bennett, Extension Forestry Professor and Specialist.

Preventing Seed Spread: What to Know Before You Pull

To prevent seed from spreading remove invasive plants before seeds are set (produced). Some plants continue to grow, flower and set seed even after pulling or cutting. Seeds can remain viable in the ground for many years. If the plant has flowers or seeds, place the flowers and seeds in a heavy plastic bag “head first” at the weeding site and transport to the disposal site. The following are general descriptions of disposal methods. See the chart for recommendations by species.

Burning

Large woody branches and trunks can be used as firewood or burned in piles. For outside burning, a written fire permit from the town fire warden is required unless the ground is covered in snow. Brush larger than 5 inches in diameter can’t be burned. Invasive plants with easily airborne seeds like black swallow-wort with mature seed pods (indicated by their brown color) shouldn’t be burned as the seeds may disperse by the hot air created by the fire.

Bagging (solarization)

Use this technique with softer tissue plants. Use heavy black or clear plastic bags (contractor grade), making sure that no parts of the plants poke through. Allow the bags to sit in the sun for several weeks and on dark pavement for the best effect.

Tarping and Drying

Pile material on a sheet of plastic and cover with a tarp, fastening the tarp to the ground and monitoring it for escapes. Let the material dry for several weeks, or until it is clearly nonviable.

Chipping

Use this method for woody plants that don’t reproduce vegetatively.

Burying

This is risky, but can be done with watchful diligence. Lay thick plastic in a deep pit before placing the cut up plant material in the hole. Place the material away from the edge of the plastic before covering it with more heavy plastic. Eliminate as much air as possible and toss in soil to weight down the material in the pit. Note that the top of the buried material should be at least three feet underground. Japanese knotweed should be at least 5 feet underground!

Drowning

Fill a large barrel with water and place soft-tissue plants in the water. Check after a few weeks and look for rotted plant material (roots, stems, leaves, flowers). Well-rotted plant material may be composted. A word of caution- seeds may still be viable after using this method. Do this before seeds are set. This method isn’t used often. Be prepared for an awful stink!

Composting

Invasive plants can take root in compost. Don’t compost any invasive plant material unless you know there is no viable (living) plant material left. Use one of the above techniques (bagging, tarping, drying, chipping, or drowning) to render the plants nonviable before composting. Closely examine the plant before composting and avoid composting seeds.

Suggested Disposal Methods for Invasive Plants 

This table provides information concerning the disposal of removed invasive plant material. If the infestation is treated with herbicide and left in place, these guidelines don’t apply.

Photo credit: Caumsett Foundation