Rake the lawn to remove dead grass and roots. The preemergent should take care of weeds before they emerge, and is applied in the spring before temperatures reach into the 50. Wait at least six to eight weeks before casting seeds to ensure there is no effect from the pesticide.
Tips warnings do not over water or you will cause erosion that will wash away the seeds do not walk over the ceded area if possible to keep from packing the soil or removing seeds with the soles of your shoes keep children and pets off the treated areas since the chemicals could be harmful.
Things You’ll Need
Look at the package of grass seed it should indicate an overseeding quantity. Fill the garden spreader with half of the recommended amount for your type of seed.
However before applying it you should check the pre-emergent to ensure the type of grass in your lawn isn’t affected.
Preemergent weed killer is meant to stop weeds from growing and is usually applied in the spring. If you have had issues with weeds and have decided to get a head start on the problem before summer pre-emergent helps you also need to overseed or reseed the yard so that you can fill in all the bare spots where weeds have grown in the past. A thick lawn helps keep weeds out by denying the seeds access to the soil through the thick blades.
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.
You can sow seeds in as little as a week or even sooner after spraying glyphosate, a systemic, nonselective weed killer. Glyphosate moves from the leaves to the roots of plants, destroying the entire plant, but leaving no residue in the soil. The chemical affects many types of plants, including weeds, grasses and desirable plants, but after the liquid is absorbed into the plant, it doesn’t pose any further threat. You can safely sow ornamental flower seeds a day after spraying with glyphosate and grass and vegetable seeds, three days after, even though the herbicide takes up to seven days to destroy weeds. If you remove the dying weeds too soon, live roots could remain in the soil, ready to regrow. Another systemic weed killer that doesn’t affect seeds is pelargonic acid.
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.
Pre-Emergence Weed Killers and Sowing Seed
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.
Many selective weed killers leave little or no trace in the soil, and they target certain plants while leaving others unharmed. Generally, these types of herbicides destroy either grassy weeds or broadleaf weeds. You can safely sow most seeds in your vegetable or flower patch a day after applying selective herbicides, such as sethoxydim, clethodim and bentazon, for grassy weeds. These herbicides only affect your desired plants if the plants belong to the grass family. For lawns, herbicides that destroy broadleaf weeds are effective, but it isn’t safe to reseed until a month after applying these products, unless the label states differently.