It makes sense to be cautious about sowing seed after using weed killer. Certain herbicides can harm sprouting seeds and young plants. However, while you must wait several months to sow seed after applying some weed killers, you only need to wait a few days after applying others. The reason for this difference lies in the effect of the active chemicals in the individual products. Read the label carefully and follow all the directions when applying a weed killer.
Sowing Seed After Applying Glyphosate
Pre-emergence weed killers prevent seeds from sprouting. They create a chemical barrier on the soil surface that suppresses seed development. What this means is, if you sow your own seed after applying a pre-emergence weed killer, the seed isn’t likely to grow. However, some pre-emergence products only affect grassy weeds, so you can safely sow most vegetable and flower seeds after applying these herbicides. The same doesn’t apply to reseeding or overseeding your lawn. Grass seed won’t sprout until a pre-emergence weed killer has decayed and become ineffective. For example, it isn’t safe to sow lawn seed until four months after applying a crabgrass preventer.
Pre-Emergence Weed Killers and Sowing Seed
Sowing seed after applying a pre-emergence weed killer disturbs the chemical barrier on the soil surface, which means that weed seeds may germinate too.
I’m not concerned about getting it perfect. If 10% of the seed I put down comes up and starts to spread over the years, I’d consider that a win. Every amount above that certainly welcome, but.
I just sprayed today, and it’s supposed to rain in 2 days (and a few days in a row). I was hoping I could toss down the grass seed tomorrow before rain, but I wasn’t sure if that’s too soon, or if it matters with this particular chemical.
Can I over-plant grass seed a day after spraying Ortho Weed B Gon? If not, how long do I need to wait (and why)?