· since pre-emergents also kill grass seed, wait 12 weeks after application to overseed your lawn. Rake through those bare spots and turn over the dirt to break up the pre - emergent compounds. Now, let’s address the question at hand: A pre - emergent herbicide prevents weed seeds from sprouting and establishing a root system. · if youre wondering when to water after pre emergent , the answer is immediately after application—usually within 24 hours—for best results. Technically, you could seed 16 weeks from the application, but that puts you in the hottest part of summer. The general rule of thumb is to wait at least 4-6 weeks after applying pre-emergent herbicide before overseeding. They typically use siduron (tupersan), which is more forgiving and allows for seeding at the same time. A garden weasel gardening tool works great for this! · seeding a lawn after applying pre - emergent herbicide can be a delicate process that requires proper timing and preparation. Pre - emergent herbicides are designed to prevent weed seeds from germinating, but they can also affect the growth of grass seeds if not managed correctly. After your 1st application of the year wait at least 7 to 10 days before doing any renovation of the lawn or seeding. Seeding is not advisable at that time. The conflict arises because the herbicide kills all germinating seeds indiscriminately, including desirable grass seed. How long after applying pre-emergent can you overseed your lawn? · overseeding involves spreading new grass seed over an existing area to thicken the turf and fill in bare patches. Learn how pre-emergents work and how to use them. There are some formulas on the market designed for overseeding compatibility. · generally, once a pre - emergent herbicide is put down in the spring, you cannot effectively seed until fall.
