Prolific Winter Annual Weeds

By Julie Barnes

Spring is around the corner. There have been many beautiful winter days beckoning us to spend time in the garden. But, don't be overzealous about garden clean up yet. The weather is still uncertain. Plants need continued protection as pollinators continue to bed down in garden debris. Yet, you can be vigilant for removing winter annual weeds. Some winter annuals begin their development in fall, forming a small rosette of leaves that overwinter until spring, as others burst into growth from dormant seed towards the end of winter, forming flowers - then seeds. Let's look at five of the most common ones that we have seen in our area - chickweed, hairy bittercress, henbit, corn speedwell, and purple deadnettle – annual weeds that are found in flowerbeds, vegetable gardens, around trees and shrubs, or in the lawn.

Chickweed

Common chickweed (Stellaria media) has small, ½ inch long, bright green elliptical leaves that are pointed at the tip. During the growing season, dainty star-shaped white flowers with five deeply notched petals will produce a seed laden dry capsule. Countless seeds can be unleashed as this splits open at maturity to germinate mostly in autumn or spring. Seeds are easily carried by animals, on footwear and even on tires. Chickweed also serves as a host to several harmful viral diseases that affect crop plants.

Hairy bittercress

Hairy bittercress (Cardamine hirsuta) is one of the earliest to sprout appearing in late winter to early spring as three to four-inch tall clumps or "rosettes" with stems that have small, rounded, green leaves. Wiry stalks poke up six to eight inches above the clumps, forming dainty white, four petal flowers at the tip that mature into long, narrow seed pods loaded with weed seeds. When ripe, a slight breeze can cause them to burst explosively flinging seeds several feet away.

Deadnettle and Henbit

Deadnettle (Lamium purpureum) and henbit (Lamium amplexicaule) are often confused. These common winter weeds belong to the mint family having characteristic square stems with opposite leaves that emerge in early spring. Both tend to grow in disturbed soil areas such as fields, gardens and areas along buildings. These upright plants parade whorls of tubular 2 lipped pink/purple flowers above an upper leaf axis from March to May. 

The leaves of Henbit are circular with rounded teeth on the leaf margin.

Deadnettle has triangular shaped leaves less deeply lobed than henbit. Sometimes the upper leaves are purple or red. Although it is called dead nettle because it resembles stinging nettle, it is not related to nettles and has no sting.

Corn speedwell l

(Veronica arvensis) (below) is found in lawns or gardens. Pretty light blue flowers with triangular shaped leaves appear on long stems maturing to a capsule.

Winter Annual Weed Control -The biggest line of defense against these fertile winter weeds is to never let them go to seed. They are easy to pull out by hand in late winter or early spring when they are actively growing. Applying a product such as Preen in fall, late winter or early spring should also help you get a jump on these weeds. This must be applied before weed seeds develop. For three months or more, it should prevent weed seeds from germinating in flowerbeds.