By Erin Watts, Department of Environmental Protection and Sustainability

Photo of a garlic mustard plant

As a natural resource specialist, I am often asked the question, “Is this a weed?” However, there is no “yes or no” answer to this question because a weed is merely an unwanted plant. I prefer the question, “Does this plant belong here?” People have carried plants and seeds from one part of the world to another for centuries. When some plants are introduced to a new area, they become invasive. These are plants you likely have seen taking over a garden or natural area. Non-native plants are also called, “exotic,” or, “alien.”

Non-native, invasive plants present a problem because all the parts of an ecosystem evolve together. When our native plants are outcompeted for light, nutrients and space, they no longer provide resources for the ecosystem. For example, spring wildflowers are disappearing, crowded out by garlic mustard (European) and Japanese stiltgrass, and trees smothered in English ivy are threatened by extra weight and decay from trapped organic material and moisture, which can kill a tree.

Therefore, invasive plants should be removed. Many invasive plants, such as garlic mustard and wavyleaf basketgrass, are easily removed by hand. Some larger shrubs, such as multiflora rose and bayberry, require cutting and digging. If possible, choose these mechanical methods over herbicides. In some cases, select herbicides are warranted to prevent persistent regrowth of certain species, such as tree of heaven, as well as for large infestations and for species that spread by roots (Canada thistle). For more information, refer to Plant Invaders of Mid-Atlantic Natural Areas, an authoritative guide with removal instruction provided by the National Park Service and the U.S. Fish and Wildlife Service.
A yard is a great place to start tackling invasives. If you don’t have a yard, there are plenty of areas that could use your help, just be sure to get the landowner’s permission. Once the risk of COVID-19 has eased, our Baltimore County watershed associations are a great source for invasive removal workshops. Learn from the pros and help protect your watershed!

Photo of English Ivy
Tips for invasive removal:
• Identify plants accurately, and avoid pulling natives.
• Wear sturdy gloves.
• Work in damp soil to get as many roots as possible.
• Remove plants before seeds develop.
Set out pulled invasive plants with your yard materials, if you're a Baltimore County resident with a separate "Y" collection day; otherwise, dispose of these plants in the trash.
• Do not put invasives into your compost at home to avoid potential spread later.
• Let vines in trees die in place to avoid breaking branches from pulling.
• Some invasives are sold in stores–don’t buy them.
Successful invasive plant removal requires a watchful eye and ongoing treatment, but a healthier ecosystem is worth it. Pulling “weeds” also helps us to unwind, so listen to the birds and enjoy.
Special thanks to the 5th grader from Rodgers Forge Elementary School who asked the question that prompted this blog post.

Photo credits: Garlic mustard (top) – Richard Gardner,; English ivy (bottom right) – James H. Miller, USDA Forest Service,