Updated: Oct 6, 2020
Winter annuals germinate and develop in the fall, overwinter as plants, mature in the spring, flower, set seed and then die during the summer. Annual bluegrass is one of the most common winter annual grassy weeds in turf. Henbit, purple deadnettle and common chickweed are other examples of winter annual broadleaves. Here, we’ll review four common winter annual weeds, plus provide tips on how to control their growth.
One of the most persistent weeds, annual bluegrass, Poa annua, is also one of the most common weeds in the United States. Leaf blades that are crinkled part way down are a key characteristic of annual bluegrass, according to the University of California, Statewide Integrated Pest Management program.
The best defense against henbit is to properly maintain turfgrass. This includes selecting the right species for the location and usage, plus proper cultural practices including mowing, fertility, irrigation and aeration.
Purple deadnettle, a winter annual broadleaf weed, germinates from seed, grows and dies in less than a year. The nectar of purple deadnettle is attractive to bumble bees, honey bees and digger bees, a group of large bees that nest in the ground, according to Michigan State University Extension. If you are trying to eliminate it with a herbicide, it is best controlled in fall or when actively growing.
Common chickweed is a prostrate, winter annual that’s found throughout North America. Common chickweed mainly blooms February to September. The small flowers have what appear to be 10 petals, but are really five deeply-cut white petals. The best time to control chickweed is in the fall or spring.