Weed of the Moment: Kochia

Posted by: Tony Koski, Extension Turfgrass Specialist

Kochia (ko-sha) (Kochia scoparia) is a very common weed found everywhere in Colorado. It can be found in rangeland, pasture, gardens, ditches and on small acreages--essentially anywhere with disturbed soils. Kochia is a native of Asia and was introduced from Europe. As a summer annual, it begins germination in early spring. With its fuzzy gray leaves, as a small plant it's not unattractive, since it forms a dense mat on bare soils. [Note: I once was asked by a homeowner if she could have a kochia lawn, since she thought it was so pretty.]

Young kochia just after germination.

As summer progresses, the plant grows taller and looks like a gangly teenager, until it breaks off in fall, turning into tumbleweeds as large as 6 feet tall. And that's how the seeds disperse. Thousands and thousands of 'em. If you've ever driven on E470 to the airport, you've likely smashed one into smithereens.

Tumbleweed. It's a big 'un!

If you have kochia in your landscape, pull it or control it while it's young. It's much easier to control as a young seedling. Plants have a very shallow taproot and can easily be pulled or hoed. A thick layer of mulch can be very effective in helping control kochia. Kochia can be controlled using a non-selective herbicide like glyphosate (Roundup) when it is young (less than 12 inches tall); mature kochia is very resistant to glyphosate and just about any other herbicide. When using glyphosate for kochia control, complete coverage of the weeds is essential or you will have poor results. Remember to apply all herbicides according to the label. Focus your efforts on cultural conditions and management. It's rare to have kochia in the lawn, unless you have thin, bare areas.

Invasion of the tumbleweeds! A backyard in Pueblo.