Do it with the spring cleanup
This is the one piece of timing worth getting right. Preen goes down best as the ground is just starting to warm — which is exactly when the spring cleanup happens.
Doing them together is not just convenient. The weeds that are already up get pulled first, and then the pre-emergent gets raked into the soil rather than left sitting on the surface. Both of those are the difference between it working and not.
Book whenever suits you. If you are a Bro Bank member it is easier still — request the service in your client portal and we take it from there.
What a pre-emergent does, and does not
It does not kill weeds you can already see. It puts a barrier across the bed that stops weed seeds rooting as they germinate. Anything already growing has to come out first — a barrier laid over live weeds is money spent on a problem it was meant to prevent.
Two things that undo it
Leaving it dry. Most granular pre-emergents need watering in to activate, and left dry on the surface they do nothing until it rains.
And digging afterwards. The barrier is a surface layer; raking or planting through it opens a gap and weeds come straight up. It also cannot tell a weed seed from a flower seed, so keep it away from anything you are sowing.
We are based in Milford and work across Oakland County and the towns around it. See what Milford neighbors say, or get a free quote.