Avoiding invasive species in the garden

Beauty can be deceiving, especially in the garden. Invasive species of plants are often pretty or ornamental. Whether homeowners purchase a plant or it shows up like a weed, an invasive species can quickly become a problem. Protect the garden and avoid allowing invasives to take root.

According to Alabama Extension Specialist Nancy Loewenstein, invasive species are non-native plants that have escaped cultivation and become weedy problems.

While it can be hard to predict which species will become invasive, some frequently seen invasive plant characteristics include:

• competitive (rapid) growth
• strong reproductive pressure (produce a lot of seeds quickly)
• easily spread seeds (wind, water, birds and other animals)
• easily establish

To access a list of invasive plants in Alabama, read the Alabama Invasive Plant Council’s publication.

More than 50 percent of the species on the Alabama Invasive Plant Council’s invasive plant list are escaped ornamentals.

“If focusing on woody species, nearly all invasive woody species are escaped ornamentals,” Loewenstein said.

If these species end up in the garden or landscape, the plants act as weeds and can become an extensive problem.

Invasives are a danger because they displace native species. This means the species replaces native plants, therefore displacing native animals, insects and soil microbes that depend on the native species.

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“As an example, non-native plants support far fewer caterpillars and other insects that songbirds depend on to rear their young,” Loewenstein said.

They can also impact water, nutrients, fire cycles, wildlife habitats, outdoor recreation, aesthetics, natural resource management and productivity.

Once an invasive plant establishes, control is time consuming and may be expensive.

The best way to stop the spread of aggressive invaders is to remove the plant entirely. For smaller species, deadheading to remove the flowers before the seeds drop is an option. Gardeners and homeowners can also pull seedlings or small plants for effective control.

Cut down larger woody species. However, the stump will likely re-sprout. Homeowners can prevent growth by treating the stump with a herbicide. You can learn more about stump treatment on the Alabama Extension website.

"Herbicides can control many species, but care must be taken to avoid damaging desirable species,” Loewenstein said. "Make sure to read the herbicide labels to ensure proper use. In all cases, it’s easier to control invasive plants when there are only a few of them rather than after the infestation becomes large and daunting."

Increase the health of ornamental plants by avoiding and removing invasive species in the garden.

Mary Leigh Oliver is a communication specialist at the Alabama Cooperative Extension Service.