Worms are beneficial to a true organics grow as long as no synthetic or psuedo organic nutrients that contain synthetics are used. Sythetic fertilziers will just kill them. Worms help keep the soil open, they breakdown organic matter, and they add diversity to you're microlife. Not to mention they're cheap, you can just use regular old baitshop worms. And from what I've read different worms stay in different parts of the soil, nightcrawlers stay in the lower portion where it's cooler.
All of this I read in skunk and was written by the rev.