Brock: Spring weeds have arrived

Published 12:00 am Saturday, April 2, 2022

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I have a little vegetable garden in my yard and the plants are looking great. The same can be said for my flowers, window boxes and the satsuma tree. But those poor cool-season weeds? They seem to be coming to an end. Pre-emerge herbicides last fall were neglected (best applied September through November) and I’ve had quite a crop. Many of these weeds are annuals and they’re going to seed as their life cycles finish.

One I especially have in mind is annual bluegrass – Poa annua. It consists of small tufts of grass that do not spread by runners but by seed. So, they’re sporadic in a lawn and not very noticeable for most of their lives. But as weather warms (now) they yellow and throw out tons of very visible seeds. This is the end of their little (yes, annual) lives and when they really ugly up the lawn.

So what to do? Absent a time machine and that pre-emerge, you can apply atrazine with some effect. But they are mature weeds, much less prone to herbicides than they were a couple months ago. You can let them finish dying and your best control option will be to mark your calendar for next fall.

Plenty broadleaf weeds (lawn burweed, sow thistle, white clover, etc.) are singing their swan songs too. These will succumb to a hearty application of trimec-type herbicides (Weed B Gon, Weed Free Zone, etc.) tank-mixed with atrazine. They are also mature now and harder to kill.

The best way to keep a weed-free lawn? Keep it healthy by mowing at the proper height and fertilizing every other month starting in April. Strong lawns tend to outcompete weeds!


If you want to know more about gardening, landscaping, or anything else horticultural, contact the St. John & St. James Parishes Horticulture Extension Agent André Brock at Also, the LSU Ag Center’s website can be accessed at with lots of user-friendly information, including this article.