Weed growing, Crabgrass Banner for Anne of Green Gardens

By definition, a weed is a plant in the wrong place. Weeds compete with garden plants for water, nutrients and even sunlight. Find out how to prevent and control weeds in your garden using organic or non-toxic methods.

Weed Identification

It’s important to know what kinds of weeds grow in your garden. Once you identify a weed you can understand its lifecycle, and then figure out when best to kill and/or prevent it. Use the National Gardening Association’s Weed Library photos to identify your weeds.


Herbicides are a type of pesticide formulated to kill specific weeds. Not all herbicides kill all weeds, so it’s best to read the label before making a purchase. Also, remember that the words “organic” or “natural” do not necessarily mean they are safe to use around wildlife. Many of these herbicides are toxic to fish, beneficial and pollinator insects.

Weeds and Butterflies

You may be surprised to know that many so-called weeds are the larval food plants of butterflies. For example, Red Admiral butterfly larvae eat burning and stinging nettle. You may want to enter your weed in the search bar of the Butterflies and Moths of North America database.

Preventing Weeds

Some weeds reproduce primarily by seed, while others reproduce by seed and/or send out roots. Weeds that use both methods to reproduce tend to be the most problematic in gardens.

No matter how much weeding and prevention you do, more weed seeds are waiting below the surface of the soil. These seeds can be buried inches or even feet and are called a “seed bank.” As you till or dig in your garden, the seeds are brought up to the surface and most sprout when irrigated.

To prevent weed seeds from sprouting, use landscape fabric or cardboard over the top of the soil. Then add 3-4 inches of mulch on top of that. Mulch is an organic material and will break down, so make sure to replace it each year. Eventually weed seeds deposited on top of the mulch will begin to grow, and to prevent this you’ll need to mulch on a yearly basis.

Soil solarization is a great way to kill weed seeds buried up to a foot below the soil’s surface. It’s done by laying clear plastic over the top of the soil during summer in climates where temperatures regularly reach 95°F. Learn more about it in Soil Solarization.

Controlling Weeds

As with controlling weed seeds, you can put landscape fabric or cardboard and a 3-4 inch layer of mulch over the top of weeds that are already growing. Certain weeds are easily controlled well by shading, while others leave parts behind that regrow once the shade is removed, like invaders from a science fiction movie.

Knowing the lifecycle of a weed can help you defeat it, although in some cases (such as Bermudagrass) it seems like the alien never dies. If you’ve defeated an “alien” weed PLEASE write and tell us your method. Sheet mulching may be the best way to do this.

Sometimes gardeners don’t have or the physical capability to hand pull or hoe their garden. If you decide to use chemicals, make sure to read the label first. Using the wrong chemical wastes time, energy and adds an unneeded toxic substance into the environment.

Mechanical Weed Control

Mechanical weed control involves using a tool or your hands. My junior college plant science teacher told our class that he pulled weeds every morning for 10 minutes as he drank a cup of coffee. He added that by the time the weekend came he didn’t have much weeding to do.

Weed Plants and Invasive Weeds

You may have heard the term “invasive” about a weed or plant. A truly invasive plant reproduces itself quickly and invades pastureland, cropland, waterways and freeways. These weeds cause multiple problems including increased flood and fire danger and cost the U.S. (and other countries most likely) billions of dollars in damage.

If a plant in your yard appears to be aggressive and you wonder if it’s an invasive species in your state, you can look it up by common or botanical name on the Invasive Weed Website.