- Invasive plants are not native and harm the environment, economy, and even human health.
- Invasive plants can be controlled long-term by utilizing a combination of control techniques and tools that are specific to their biology.
- Replace invasive plants with competitive native plant species that are appropriate for the soil and growing conditions (Refer to: Table 1)
What are invasive plants and why should they be removed?
Invasive species are non-native organisms that cause harm to the environment, economy, or human health with damages costing the United States approximately $120 billion every year (Simberloff, 2013). Invasive plants alter the native ecosystem and disrupt biodiversity in forests, meadows, and wetlands. These species have unfair advantages over native plants, especially in human-disturbed habitats. They reproduce aggressively in multiple ways, and at a much faster pace than our indigenous plants.
Why should communities and residents be concerned about invasive plants?
Invasive plants are the greatest threat to our natural environment, other than habitat destruction. Our native environment supports native plant biodiversity crucial for the survival of insect and bird populations and the entire food chain. Invasive plants also cost our national economy billions of dollars annually, devastate agriculture, and diminish the quality of parks, natural, and recreational areas.
For more information on how invasive plants impact ecosystems, refer to our Invasive Species resource page. For information regarding the retail sale of invasive plants, please visit the Maryland Department of Agriculture Invasive Plant Control page. Visit the Maryland Invasive Species Council website to find a representative list of invasive species in Maryland. For a complete list of species and their degree of concern, consult the Mid-Atlantic Invaders Tool.
The term ‘native’ refers to a plant species that occur naturally in an ecoregion and habitat over the course of evolutionary time. To learn more about native plants, please refer to What is a Native Plant?
Controlling invasive plants long-term
Because of the aggressive nature of invasive plants, it is unlikely that one treatment will completely eradicate a population. Unless control methods are used before establishment, it may take months to years of observation and management to suppress new growth of the undesired plants.
We recommend a methodical approach to management:
- Identify the problem,
- Learn more about the plants’ biology,
- Utilize a variety of control methods and tools to eradicate,
- Replace the area with competitive plantings, and
- Continue to monitor the area and take action as needed.
- Proper plant identification is the first step to invasive plant control. Before implementing any methods, consult HGIC’s Ask Extension or contact your local county Extension office.
- Use the Invasive Species page to find common invasive woody and herbaceous plant species in Maryland.
- Early detection and eradication are best when plants are smaller or more manageable. Taking any early action will help slow the spread. Any action, any time, can have a profound impact stopping invasives.
- Understanding the biology and growing habits of an invasive plant species will help you create an implementation plan for successful control.
- (PDF) Plant Invaders of Mid-Atlantic Natural Areas provides great guidance for how to approach control and handle the species in question.
- Recognize your challenges; if a neighbor has English ivy or Callery pear, you’ll want to identify those plants as needing more attention for removal. Better yet, convince your neighbors to join the effort in eradicating their invasive plants too!
- Use a variety of control methods as part of a “toolbox” approach; physical and mechanical removal, biological control (rare), and chemical control as a last resort.
- Some common mechanical treatments include repeat mowing, pulling, smothering with cardboard/newspaper/wood chips, cutting, or livestock grazing. Mechanical removal is recommended for small spaces.
- Chemical control can include different methods: cut stump, “hack and squirt”, basal bark, and foliar applications. The treatments are different depending on the species, so it is important to understand the plant’s biology and growth habits. It is highly recommended to use (PDF) Plant Invaders of Mid-Atlantic Natural Areas as a guiding resource, or HGIC’s web pages.
- Invasive Grass Control
- Invasive Herbaceous Plant Control
- Invasive Shrub Control
- Invasive Vine and Groundcover Control
- Replace the area with native plantings as soon as possible. Exposed or disturbed areas can easily be taken over again by the invasive species you have worked so hard to remove. Here are some ideas and recommendations to consider:
- If the space is small enough, homeowners may choose to remove all undesirable plants at one time.
- With larger spaces or wood lots, homeowners may choose to address the area in manageable sections or prioritize spaces for removal effort. For example, a homeowner may choose to remove Japanese barberry from the existing landscape to replace it with a native alternative, such as Virginia sweetspire.
- Even without funds to purchase replacement plantings, small efforts to control invasive plants can have a big impact. For example, cutting out a 12” section of English ivy vine that is growing up the trunk of a large landscape tree. For better efficacy, it would be recommended to paint the cut ivy surface with glyphosate or another herbicide approved for woody vine control.
- Please refer to the Recommended Native Plants (Table 1) section below for specific species to plant.
- Even after initial removal efforts, continue to observe and suppress invasive plant growth as it returns. Monitor the area as you participate in replanting, and spot-treat as necessary. Use different methods of control and treatments depending on the time of year, plant species, and severity of invasion.
A comment on the use of pesticides personal protective equipment (PPE)
When used properly and according to the label, herbicides are a very effective tool in the removal of alien plant species. It is recommended you wear proper PPE to protect yourself. Also, familiarize yourself with information about using glyphosate and alternatives as a control method.
Replacing invasives with recommended native plants
In order to compete with the growing habits of invasive plants, it is recommended you choose native species that can be considered “aggressive”. It is crucial to consider growing conditions and soil type when you choose replacements.
Can native plants be invasive?
The term “invasive” is usually in reference to an alien species that has been introduced to an area. That is why native plants are referred to as “aggressive” instead. Some of these species are too overwhelming for a small or tidy landscape but may work perfectly in the battlegrounds of disturbance.