I believe the very best time to use crabgrass preventer is in the late fall, in the next few weeks. Second best time is in the very early spring assuming bare ground, say first couple weeks of March.
However, my mother wants to aerate and overseed in the late April so I am telling her we should spread the HALTS right after we get up all the leaves. If we do the HALTS in early March, her overseeding would be HALTed so to speak. Her 'friends' think I am wrong and she should do the HALTS in the spring.
I believe the crabgrass seeds are laying around and it doesnt matter when you hit them with the HALTS as long as you do it before they sprout. ie, April/May is way too late.
Am I right or wrong?