DIY Frequently Asked Questions / Lawn Weed Control')">
Weeds are classified as grassy (such as crabgrass), broadleaf (such as dandelions and plantain), annual or perennial.
Weed seeds can lie dormant in the ground for several years, then grow again when conditions are right.
Spring is the best time to control broadleaf and grassy weeds when they are small and vulnerable. Weed killers are formulated to work best in temperatures between 60°F and 85°F.
Pre-emergent herbicides attack weeds before they break the surface of the soil. Apply them early in the spring. Post-emergent herbicides attack the plant after it begins to grow.
Selective herbicides kill certain plants but do not harm others. Non-selective herbicides will kill all vegetation they touch.
Do not rake or dethatch lawns after applying a pre-emergent herbicide. It will destroy the protective barrier the chemical has created.