Kentucky garden expert shares simple rule for stopping invasive plants before they spread

A productive garden can quickly become a frustrating mess when invasive plants begin spreading through beds, lawns, and along fence lines.

But one simple rule can make them much easier to manage: determine whether the invader is an annual, a herbaceous perennial, or a woody plant before deciding whether to pull, spray, or cut it back, as The Courier Journal explains.

Here’s what to know

Timing and technique both depend on how a weed survives from one season to the next, said Paul Cappiello, executive director at Yew Dell Botanical Gardens. In a gardening column, he described himself as “what I call a slash and burn gardener” — an approach that can work well when matched to the plant’s growth habit, according to The Courier Journal.

Because annual weeds last just one growing season, their real staying power comes from the seeds they drop into the soil. “The key to controlling annuals is to keep them from going to seed,” Cappiello wrote.

Herbaceous perennial weeds present a different problem: even after their top growth dies back, the roots remain alive through winter and can send up new shoots in spring.

Among the hardest plants to clear are woody invaders such as Amur honeysuckle, kudzu, and porcelain vine, which often require cut-stump treatment to prevent them from coming back.

More background

Invasive plants do more than make a yard look messy or overgrown. They compete with vegetables, flowers, shrubs, and native plants for water, sunlight, and soil nutrients, which can reduce harvests and weaken desirable plants.

Annuals can leave behind seed banks that linger for years, while perennial and woody invaders store energy underground, making them hard to eliminate with occasional cutting alone.

What may look like a simple one-time cleanup project can turn into an ongoing battle when gardeners miss the right timing or fail to follow through.

What can be done?

It’s best to take action early on annual invaders — remove them by pulling or cutting before they start to set seed. If those seeds are allowed to spread, cleanup becomes much harder and may require repeated hand-weeding or pre-emergent weed control in the following growing season.

When herbaceous perennials cannot be pulled, late summer to early fall is the preferred time for systemic herbicides, Cappiello said, according to The Courier Journal. At that point in the year, the plants are moving resources down into their roots for winter, which helps carry the treatment further through the plant.

With woody invasives, a cut-and-treat approach is often the most effective option. Gardeners can cut the plant near the base and quickly apply an appropriate herbicide to the fresh stump, which The Courier Journal says can help stop regrowth from the roots.

People who prefer to start with lower-impact options can focus on early removal and consistent maintenance, and explore this resource on controlling weeds without chemicals for additional strategies.

For Cappiello, the rule is simple when an aggressive plant appears where it does not belong: “Essentially, if you’re a plant and you show up uninvited to my garden, you are generally going to be classified as an unwelcome invader.”

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