How to Dispose of Invasive Plants Safely

Do not compost it. Bag the roots, tubers, bulbs and any part with seeds, seal the bags, leave them in full sun for several weeks, and put them in the trash. Compost piles and municipal yard-waste programs can spread fragments instead of killing them, and one surviving piece can start a new patch.

That is the short answer for the plants most homeowners pull: Japanese knotweed, lesser celandine (fig buttercup), garlic mustard and tree of heaven seedlings. The rest of this page is about the exceptions, because the right route depends on what part of the plant you are holding. If you have not chosen a method yet, the five-step removal guide starts with identification and state rules.

Sort the debris before you bag it

The two sources disagree on one point, and the disagreement matters. Penn State Extension says flatly: do not compost plant material. The Connecticut guidelines allow composting of some species once the material is completely dead and dry, but they list exceptions that must never be composted, including fig buttercup and Japanese knotweed. If you are not sure which plant you have, treat it as an exception and bag it.

The bag-and-bake method

1. Bag it. Use heavy-duty plastic bags. Penn State Extension recommends double bagging as a precaution.
2. Seal it. Tie each bag closed so no fragments or seeds can escape.
3. Leave it in full sun for several weeks. Penn State Extension calls this solarization. The heat sterilizes seeds and destroys roots and other plant parts.
4. Put it in the regular trash. After solarization, the material can go out with household trash.
5. Check the bag before you move it. If it has torn or leaked, bag the whole thing again.

If you treated the plants with herbicide instead of pulling them, leave the dead material where it stands when you can. The Connecticut guidelines call this advisable, because moving treated plants can still spread seed.

Why composting fails

A compost pile is not a sterilizer. Penn State Extension notes that seeds and root fragments can survive the composting process and then spread wherever the compost is used. The Connecticut guidelines add a second problem: some species spread from rhizomes, tubers or bulbs that survive composting. That is why the “never compost” list exists.

The same logic applies to yard waste. If your town sends yard waste to a commercial compost site, do not put invasive plants in that bin. The finished compost may be sold or given away.

What your state allows

Disposal rules are set by states and towns. Two examples show how much they vary.

Connecticut. The Connecticut guidelines cite state law: it is illegal to transport material of a species listed as invasive under Connecticut General Statute Sec. 22a-381d, with an exception for moving plant material in order to eradicate it. Burning, where the town allows it, goes through the local open burning official. Herbicide use in aquatic environments needs a permit from the Connecticut Department of Energy and Environmental Protection. Applying herbicide on property you do not own requires a valid pesticide applicator’s license.

Pennsylvania. Penn State Extension’s guidance is to keep invasive plant material out of compost, bag and solarize it, and then trash it. Burning is allowed only where permitted, in small quantities, and only after checking local rules.

For your own state, call your state agriculture department or county waste authority and ask two questions:

• Is yard waste here composted or landfilled?
• Is there a designated drop-off for invasive plants?

If yard waste is composted, keep invasive material out of it. If there is a designated drop-off, use it and follow any bagging instructions.

Water, soil and tools

Water. Never dump water garden or aquarium plants into a pond, stream or storm drain. Penn State Extension is explicit that this is how many aquatic invaders start new infestations. The same page notes that plant fragments can survive several days out of water, so clean boats, trailers and gear before leaving a launch.

Soil. Do not move soil that contains roots, rhizomes or tubers. The Connecticut guidelines treat soil and sediment with viable plant parts as material that must be managed, not just shoveled somewhere else.

Tools. Penn State Extension advises sanitizing shovels and pruners before using them on desirable plants, and suggests disposable gloves. Invasive plants can carry pathogens and insects as well as seeds.

The one rule that covers most of it

If you remember nothing else: bag it, bake it, trash it. Do not compost it, do not put it in yard waste, and do not move it to another property. If you are trying to avoid herbicides altogether, how to get rid of invasive plants without chemicals ranks the non-chemical methods and says where they fail.

Related WildScope pages

• Prevention guides for keeping new infestations from starting.
• Lesser celandine removal and poison hemlock removal for the two spring jobs that produce the most debris.
• Garlic mustard removal and Japanese knotweed removal for plants where every fragment counts.
• Tree of heaven removal for a tree that regrows from the roots.
• Mile-a-minute weed for an annual vine whose fruit can keep ripening after you pull it.