Gardening is a rewarding hobby, but even the most seasoned gardeners know the struggle of keeping unwanted plants—weeds—from taking over. Understanding what a weed is and how to control it is the first step toward a healthy, thriving garden.

What is a Weed?

A weed is simply a plant growing where it is not wanted. While some weeds can be beneficial to wildlife, provide nutrients to the soil, or are even edible, they can also become a nuisance. They compete with your desired plants for water, sunlight, and nutrients, and can choke out your prize-winning tomatoes or beautiful flowers.

The key to effective weed control is to identify the type of weed you are dealing with. We categorize weeds based on their life cycle, which helps determine the best way to get rid of them.

Types of Weeds

• Annual Weeds These weeds live for just one growing season. They sprout, grow, produce many seeds, and then die. Because they spread so easily by seed, the best way to control them is to prevent them from flowering and setting seed in the first place. Crabgrass and ragweed are common examples.
• Biennial Weeds These weeds have a two-year life cycle. In their first year, they establish a strong root system and a low-growing rosette of leaves. In the second year, they grow a stalk, flower, produce seeds, and then die. Common burdock is a well-known biennial weed.
• Perennial Weeds Perennial weeds are the most persistent. They can live for many years and often return season after season. They not only spread by seed but also through their root systems, which can be extensive. They use rhizomes (underground stems) or tubers to store energy, making them difficult to eliminate. Dandelions and bindweed are classic examples of perennial weeds.

Weed Control Measures

• Prevention: The best defense is a good offense. Prevent weeds from taking over your garden by adding a layer of mulch, which blocks sunlight and keeps seeds from germinating. You should also check any new plants or soil you bring into your garden to ensure you are not introducing weed seeds.
• Hoeing and Cultivation: Using a hoe is great for getting rid of small weeds. It is important to use a shallow hoeing technique to avoid bringing new weed seeds buried deeper in the soil to the surface.
• Pulling: For perennial weeds, pulling them out completely, including the entire root, is essential. This is easiest to do after a good rain when the soil is loose.
• Herbicides: Herbicides can be a useful tool, but they should be used carefully. Pre-emergent herbicides are applied before seeds germinate to prevent them from sprouting. Post-emergent herbicides are used on weeds that have already sprouted and are actively growing.

Common Weeds and How to Control Them

Annual Weeds

• Barnyardgrass: This grass can grow up to five feet tall and thrives in moist soil. It has erect, hairless stems and a reddish-purple seed head.
• Control: The key is to prevent it from producing seeds.
• Crabgrass: A pale green summer annual that forms dense patches. Its two types, smooth and large, are both summer annuals.
• Control: Use a pre-emergent herbicide in the early spring before soil temperatures reach 55°F. For existing plants, a post-emergent herbicide can be applied.
• Witchgrass (Fall Panicum): With its zig-zag stems and rounded profile, this weed is a fast grower. The head breaks off and spreads its seeds like a tumbleweed.
• Control: The most effective method is to prevent it from producing seeds.
• Ragweed: A shallow-rooted annual that reproduces by seed.
• Control: It is easily managed by cultivation or mowing before it goes to seed.

Biennial Weeds

• Common Burdock: This large, coarse plant has an edible taproot in its first year and produces a stalk with flowers and seeds in its second.
• Control: General biennial weed control involves preventing seed production in the second year.

Perennial Weeds

• Dandelion: This very common perennial spreads by wind-borne seeds and its deep taproot.
• Control: To eliminate it, you must remove the entire taproot.
• Bindweed: Also known as wild morning-glory, this is one of the toughest weeds to get rid of because its roots can grow up to fourteen feet deep.
• Control: Aggressive and constant weeding is necessary to stress the plant and deplete its stored nutrients.
• Canadian Thistle: This aggressive, creeping perennial spreads by both seeds and a root system that can grow up to fifteen feet horizontally.
• Control: Constant weeding and hoeing will help stress the plant and eventually help to eliminate it.
• Quackgrass: Also known as witchgrass, this perennial weed spreads by seeds and rhizomes. Tillage can break up the rhizomes, and each piece can grow into a new plant.
• Control: If you choose to till, you must be persistent and not allow new plants to grow more than a few inches.

By understanding the life cycle of the weeds in your garden, you can choose the right control method to keep them from taking over.