How To Properly Dispose of Invasive Plant Species

Invasive species pose a significant threat to ecosystems, agriculture, biodiversity, and human health. These species can spread rapidly, outcompeting local species, disrupting food chains, and causing long-term ecological damage that affects not only wildlife but also agricultural productivity and public health. Pennsylvania alone has identified over 300 invasive plants, pathogens, and animals that currently or potentially threaten the state’s environment and economy. For an updated list of these harmful species, including plants, pathogens, and insects, refer to the Pennsylvania Governor’' Invasive Species Council's article, Invasive Species of Concern for Pennsylvania.

One of the key challenges in managing invasive species is ensuring they are properly disposed of after removal. Some species, such as Japanese knotweed, Fig Buttercup, Goutweed, Spotted knapweed, Canada thistle, Cypress spurge, Leafy spurge, Garden loosestrife, and Star-of-Bethlehem, are notorious for their resilience, as they can resprout from small root or stem segments, or bulbs, making improper disposal a serious risk for further spreading. Effective disposal methods are, therefore, essential to prevent reinfestation, preserve conservation efforts, and stop the cycle of invasion. Properly removing and destroying invasive species is a crucial step in protecting ecosystems and preventing their re-establishment in new locations.

Here are some ways to dispose of these invasive plant species.

1. Do Not Compost Plant Material

Many invasive species are highly resilient, with seeds or root fragments capable of surviving the composting process. Instead of breaking down, these materials can spread to new areas when compost is used in gardens or landscaping. To prevent this, dispose of invasive plant material in a way that ensures it cannot be reused—such as by taking it to a designated disposal site for invasive species.

2. Bag, Seal, and Solarize Plant Material

When removing invasive plants or their components (e.g., seeds or roots), it is essential to bag and seal them in heavy-duty plastic bags to prevent any fragments from escaping and spreading. Double bagging is a recommended precaution. For added effectiveness, place the sealed bags in direct sunlight for several weeks. The intense heat generated during this solarization process will sterilize seeds and destroy roots or other plant parts, ensuring the invasive material cannot cause further spread. After solarization, the material can be disposed of safely with regular trash.

Species such as spotted knapweed, purple loosestrife, Japanese knotweed, and giant knotweed should always be bagged and solarized before disposal to prevent their continued spread.

3. Burn Plant Material

Where permitted, in small quantities, burning the plant material is an effective method to ensure the complete destruction of seeds and plant parts. If burning is used, consult local regulations to confirm it is allowed and follow all safety guidelines.

4. Diseased or Infested Plant Material

Some invasive plants may also harbor pathogens or insects that could be problematic for the non-invasives in the landscape if they spread. It is wise to handle the invasive plants as though they may be carrying disease-causing organisms, even if signs or symptoms are not apparent.  Be sure to sanitize any shovels, pruners, or other tools before using these tools on desirable plants, and consider using disposable gloves to avoid spreading disease.

The bagging/trash method detailed above is also effective for disposing of desirable plants that are infected with diseases, preventing the spread to other plants. Solarization is not a recommended approach for eradicating disease in this case, as many pathogens can survive the heating and desiccation achieved by this method.

5. Aquatic Plants

Invasive aquatic plants are disposed of using methods similar to those mentioned above, with a few exceptions.

• Small quantities of plants should be frozen for at least 24 hours and then discarded in the trash.
• Medium amounts of aquatic plants should be dried. After drying, plants should be discarded in sealed plastic bags in the trash or allowed to decompose in upland areas where the plant parts will not be washed back into the waterway.
• Large quantities of plants can be allowed to dry, followed by upland decomposing or burning in accordance with federal, state, and local laws and guidelines.

Discard All Aquatic Plants Responsibly

Many invasive aquatic plants are introduced to new areas when water gardeners or aquarium owners dispose of plants in a local water body. Never dispose of aquatic plants from fish tanks or water gardens into natural systems. Additionally, ensure that water gardens are located away from natural water bodies, where floods, animals, or other factors could contribute to the release of aquatic plants (or animals) into the environment. Water hyacinth (Pontederia crassipes, formerly Eichhornia crassipes) is a common ornamental water garden plant mistaken as an annual in Pennsylvania. Water Hyacinth can survive Pennsylvania winters and overtake natural waterbodies when released or improperly discarded.

Dispose of Invasive Aquatic Plants in the Trash – Not the Composter

Seeds, rhizome roots, and other reproductive structures can survive composting. Never compost aquatic plants, especially near a waterway. Aquatic plants like Yellow Floating Heart (Nymphoides peltata) can reproduce via specialized underground roots called rhizomes, which can survive the composting process, spreading to new locations when the compost is distributed. Instead of composting, choose an alternative method of disposal such as those above.

Remove Aquatic Vegetation from Vehicles, Boats, Trailers, and Gear

Avoid transporting aquatic vegetation on your vehicle, boat, trailer, motor, gear, and in water-containing devices. Many aquatic plants can reproduce through fragmentation, and reproductive structures can survive several days out of water. Hydrilla (Hydrilla vercillata) is an invasive aquatic plant that spreads through many methods, including fragmentation. One broken piece of Hydrilla can begin a new infestation if introduced to a new water body. Whether you have been recreating or removing invasive aquatic plants, leave the plants on-site in the trash, designated disposal area, or upland away from the water.

For more information about aquatic invasive species, visit the Pennsylvania Sea Grant or the Penn State Extension websites.