When Does Spring Weed Control Begin?
Timing is everything when it comes to spring weed control. Normally, the blooming of forsythia will approximate the time of crabgrass germination and provide a window of several weeks to apply pre-emergent herbicide.
While the flowering of forsythia is a good cue, crabgrass germination actually occurs after the soil temperature has reached 55ºF for several consecutive days.
What is a pre-emergent herbicide?
A pre-emergent herbicide is a weed killer applied prior to the emergence of the weed from the soil.
Chemicals like dithopyr (Dimension) and pendimethalin (Lesco's Pre-M, Scotts' Halts) prevent all seeds from germinating, including grass seed. Grass seed cannot be applied for 6-12 weeks after application, depending on the specific product.
The chemical siduron (Tupersan) prevents only weed seeds from starting, allowing grass seed germination. It is costlier and usually used sparingly.
Corn gluten meal is an organic alternative initially used as feed on hog farms but discovered to have pre-emergent characteristics.
Get a head start on broadleaf weeds.
These measures will give you a great head start on the weeds and provide an advantage to the turf so you can spend more time enjoying the lawn.