With winter’s icy grip still firmly in place throughout much of the country, there’s probably not much for you to do with the lawn and garden right now. But someone else is hard at work out there. As you read this, winter annual weeds are slowly spreading their roots and plotting a turf takeover. Others have already established and are biding their time under the snow, just waiting for the first few warm days of spring. Luckily, winter annual weeds are easier to control then some of the more stubborn spreading perennials, and if you catch them soon enough you can prevent most major infestations.
Weed Life Cycles
Weeds can be classified by their life cycles – annual, biennial or perennial. Perennial weeds can live for multiple growing seasons. They tend to spread and creep using specialized roots. Biennial weeds take two years to complete their life cycles, usually forming a rosette during the first year and flowering the second year. Annual weeds have taken a different strategy. They accomplish their entire life cycle in one year. To do this, they establish quickly and produce an immense amount of seed. Within the annuals we have the summer annuals that germinate in the spring, grow during the summer, produce seed in the late summer, and die with the arrival of cold weather. On the other hand, winter annuals germinate in the fall or winter and mature in the spring. It’s this odd life cycle that can catch some gardeners off guard in the early springtime.
Winter Annual Weed Identification
Proper identification is key to controlling winter annuals. Here are some of the most common:
- Common chickweed– This winter annual grows in cool, moist areas. It can be identified by its bright green, elliptic shaped leaves that point at the tip. It produces white star-shaped flowers. Chickweed is widespread throughout the country and is easily spread by seed.
- Henbit – A member of the mint family, henbit can be identified by its square stem and purple flowers. It can grow up to a foot tall.
- Shepherd’s purse– The winter annual forms a rosette similar looking to the dandelion. It produces a long stem topped with a small cluster of white flowers. Shepherd’s purse can be easily identified by its unique heart-shaped seed pods.
- Annual bluegrass– One of the most problematic winter annuals, this grass weed loves to invade lawns and golf courses where its green apple color stands out like a sore thumb. Eradication is almost impossible, but there are some practices that can keep it under control.
- Cheatgrass– Another winter annual grass weed, cheatgrass can be identified by its light green color and feathery seed head. Cheatgrass is one of the worst weeds out there and contributes to several major wildfires every year. It’s not usually a problem in most residential lawn and gardens, but it wreaks havoc in pastures and rangelands. Every effort should be made to control its spread.
- Purple deadnettle– This winter annual is similar in appearance to henbit. Purple deadnettle has a fuzzy texture and purple tinted leaves. I’ve always considered it more visually appealing than most weeds. Some folks even report that it’s good to eat, but I think I’ll pass on this one.
Prevention and Removal of Winter Annual Weeds
The best way to prevent and control winter annual weeds in your turfgrass is to maintain a healthy lawn. A thick, strong lawn should easily out-compete these winter annuals. It’s only when a lawn is establishing or thin that these weeds can become a problem. In the garden, winter annuals can be easily removed by hand-pulling, hoeing or tilling. Unlike stubborn perennial weeds, annuals tend to have shallow root systems. Be sure to remove them early enough in the spring before they flower and set seed. Herbicides are not usually necessary for winter annuals since they will quickly die after flowering in the spring anyway. If needed, pre-emergent herbicides can be used in the late summer or early fall to prevent winter annuals from germinating. Remember all chemical herbicides should be used as a last resort.