Common lambsquarters (Chenopodium album) is an annual broadleaf weed that invades lawns and gardens. It was once grown for its edible leaves, but it is best kept out of the garden because it harbors viral diseases, which can spread to other plants. Keep reading to learn more about how to identify lambsquarters before this weed gets out of control.
How to Identify Lambsquarters
Removing lambsquarter from the lawn and garden effectively is easier once you know how to recognize this weed. The leaves of young lambsquarter seedlings are green with a slight bluish tint on top and reddish purple undersides. The foliage of the youngest seedlings is covered with clear, shiny granules. The granules later turn to a white, powdery coating that is most noticeable on the undersides of the leaves.
Mature leaves are oblong or lancet-shaped, wider near the stem than at the tip, and pale, gray-green in color. They often fold upward along the central vein. The leaf edges are wavy or slightly toothed.
The height of a lambsquarter weed varies from a few inches (8 cm.) to 5 feet (1.5 m.). Most plants have a single central stem, but they may also have a few rigid side stems. The stems often have red striations. Tiny, yellow-green flowers bloom in clusters at the tips of the stems. They usually bloom from July to September, but can bloom early in the season as well.
Lambsquarter weed reproduces only through seeds. Most lambsquarter seeds germinate in late spring or early summer, although they can continue to germinate throughout the growing season. The plants flower in late summer or early fall, and are followed by an abundance of seeds. The average lambsquarter weed plant produces 72,000 seeds that can live in the soil and germinate 20 years or more after they are deposited.
Lambsquarter control in the garden begins with hand pulling and hoeing to remove the weed and mulching. Lambsquarter has a short taproot, so it pulls up easily. The goal is to remove the weed before it matures enough to produce seeds. The plants die with the first frost and next year’s plants grow from the seeds they leave behind.
Consistent mowing to keep lawns at the recommended height will cut down lambsquarter weed before it has a chance to produce seeds. Aerate the lawn if the soil is compacted and minimize foot traffic over the grass to give the lawn a competitive edge over lambsquarter. Maintain a healthy lawn by following a regular schedule of watering and fertilization.
Herbicides also help control lambsquarters. Pre-emergent herbicides, such as Preen, prevent the seeds from germinating. Post-emergent herbicides, such as Trimec, kill the weeds after they germinate. Read the label on the herbicide product of your choice and follow the mixing and timing instructions exactly.