GardenLine | Yard & Garden | The Common Chickweed

This column is provided as an extension service by the Division of Extension and Community Relations and the Department of Horticulture Science, University of Saskatchewan.

As the name implies, this is one of the most common weeds encountered by the homeowner. It can spread over a large area, but it is a small, delicate plant that does not usually pose serious problems. Numerous plants in a small area compete with vegetables and ornamentals for nutrients and water, thus reducing the yield of the desirable plants.

Origin: Chickweed is native to Europe, where it is also a very common rural and domestic weed. Common chickweed (Stellaria media) is the most prevalent in Saskatchewan, but there are other varieties of chickweed encountered in the province.

Description: Chickweed can act as either an annual or a winter annual. Unlike annuals, which survive for only one season, winter annuals germinate in fall to produce small plants (rosettes). Early the following spring, these rosettes continue their rapid growth because of the lack of competition from other plants. By early summer they have dispersed their seed, which can germinate either in fall or the following spring.

Common chickweed spreads rapidly by both seed and stem rooting. Where the ground-hugging stems come in contact with the soil, roots form from the nodes. Single plants are usually only a few centimeters tall, although if in competition with other plants they can be as tall as 30 cm. Each plant can spread over an area about 50 cm. in diameter.

The leaves are small, rounded and pointed at the tip. Leaves are found in pairs, opposite each other on the stems. Side shoots are common at the base of most leaves, giving the plant a matted appearance. The flowers are small, white and fairly inconspicuous. Flowers can occur from early spring up to killing frost, producing many seeds annually.

Habitat: Common chickweed spreads well partly because it tolerates partial shade, and in fact prefers cool, moist and shaded areas. It can often be found growing in the shade of vegetables and ornamentals. Any area left open and exposed is susceptible to invasion, even if it is sunny and drier. Healthy lawns are very competitive and usually resist attack by chickweed; however, lawns under stress or thinning are very much susceptible.

Control: Chickweed is resistant to 2,4-D; for control, other herbicides must be used. A mixture of three herbicides is often used - dicamba, mecoprop and 2,4-D. This mixture is commonly sold under the trade names Killex and Trimex. Applied in the fall, this herbicide mixture is very effective in controlling the winter annual rosettes, and is preferred by most homeowners. Spring applications are also effective, but greater care must be taken not to damage other plants from drift.

If using a watering can to apply the mixture, rinse the case three or four times with a soap solution before using it for watering other plants. These herbicides can often imbed themselves into the containers. Even a slight residual in the container can seriously damage sensitive plants. If, after using the mixture you find a new infestation of chickweed, it is probably because that seed which has been deposited for a number of years is now growing. It takes a number of years to control this weed.

An alternative method of controlling this weed in the ornamental beds it to use the herbicide trifluralin, sold under the name Garden Weed Preventer by CO-OP. This herbicide, applied to the soil surface in the spring, will prevent germination of several broadleaf and grassy weeds. Note that it is not to be used in the garden.

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Sustainable horticultural information, offered free of charge to the public with the support of the University of Saskatchewan Extension Division, the Department of Plant Sciences and the Provincial Government.