Hairy bittercress (Cardamine hirsuta)

Hairy bittercress (Cardamine hirsuta)

Has spring truly arrived in Maryland? I think so – I’ve seen bluebirds, heard Killdeer (they fly at night, singing “kill-deer, kill-deer”…) and, my favorite, the spring peepers are peeping after a long winter’s slumber.


Are you seeing a lot of weeds growing in your lawn and flower beds? I have seen tall white flower heads several inches above the grass in many lawns, from Olney and Rockville to Bethesda and North Potomac. What we’re seeing is most likely hairy bittercress (Cardamine hirsuta), a winter annual weed. There are other common winter annual weeds as well, such as chickweed, dead nettle, henbit and others.


“But why do I have weeds?” you might ask, aren’t we treating* for them? Weed seeds exist in almost all soils and remain viable for many years, so weeds remain a perpetual threat to germinate and grow. A good thick lawn is the best weed control; yet weeds, much like Robert E. Peary, “will find a way or make one”.


Winter annual weeds have a distinct advantage over your lawn grasses because winter annuals germinate and grow while your lawn is asleep (“winter dormancy”). So, even though it’s very cold outside with lots of snow cover, winter annuals are growing and, as soon as the warmer spring weather arrives, the winter annuals spring up a tall flower spike that quickly turns to seed-heads.


There’s no way to treat for winter annual weeds over the winter (it is too cold!), so they must be addressed after they germinate in the spring. Mowing off flower-heads before seeds can form helps and broadleaf herbicides* can also be effective as a post-emergent to control those pesky winter annual weeds.


*George Leventhal and the Montgomery County Council are considering a ban on the herbicides that you and I can legally use to control weeds (Bill 52-14). These herbicides are safe and effective when used according to their labels. Losing these important tools will make it almost impossible to control weeds in your lawn without damaging your lawn in the process.


Please let Mr. Leventhal, Ms. Floreen, Mr. Hucker and Mr. Berliner know that you oppose Bill 52-14.


Have a great spring!

Eric Wenger and the Staff at Complete Lawn Care

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