[lilmarvin4064]

Most selective broadleaf herbicides do have a residual, I believe. Speedzone is an ester formulation (of systemic herbicides and a small amount of carfentrazone-ethyl, a contact herb..) and the label says to wait a week before seeding. Most amine formulations recommend waiting 3 to 4 weeks such a Trimec, Three-way, Momentum, etc.

However, as long as the herbicides aren't contacting the soil in excessive amounts you could realistically seed as soon as the the chemical dryed, if the weed canopy is thick enough.

I have spot-sprayed broadleafs in yards with Momentum using a backpack with a fan tip, core aerated (lawn dry by the time I finished), and spread seed with great results.