Pre-Emergent Herbicides FAQ
What does a pre-emergent herbicide do?
A pre-emergent herbicide prevents weed seeds from establishing by stopping germination or early seedling development, so it must be applied before weeds emerge. It does not kill existing weeds. Pre-emergents are the preventive half of weed control, creating a barrier that stops new weeds while post-emergents handle those already growing.
When should I apply pre-emergent herbicide?
Timing is critical: apply before target weeds germinate, which depends on the weed and the season, often early in the growth period before soil temperatures trigger germination. Applied too late, after weeds emerge, a pre-emergent does nothing. Matching the application to the germination window of the target weeds is the single most important factor in pre-emergent success.
Why does pre-emergent timing matter so much?
Because pre-emergents only stop germinating seeds and do not kill established weeds, applying after weeds emerge wastes the product entirely. The window between when you can apply and when weeds germinate is what determines effectiveness. Getting the timing right, ahead of germination, is the difference between a season of prevention and no benefit at all.
Can I use pre-emergent and post-emergent together?
Yes, and a complete program often uses both: pre-emergent to prevent new weeds and post-emergent to control those that emerge or were already present. They address different parts of the weed problem. Combining them, timed correctly, gives more complete season-long control than either approach alone.
Will pre-emergent herbicide affect grass seed or new plantings?
Yes, this is a key caution: pre-emergents that stop weed seeds generally also stop desirable seeds, so do not apply before seeding turf or expect new grass seed to germinate through a pre-emergent barrier. Coordinate pre-emergent timing with any seeding plans, since the product cannot distinguish weed seeds from the grass seed you want to establish.
Can pre-emergent herbicides be ordered in bulk?
Yes. Pre-emergent herbicides are stocked in commercial quantities and concentrates with volume pricing by quote. Operations running weed prevention programs benefit from having product on hand to apply within the critical pre-germination window across their properties, applied according to the label.
