We spread it in an area where there is extremly sparce grass, Casey was just tearing it up with her hooves when she walked. We don't have a spreader, we took our tractor and used the bucket to dump it out and a rake to spread it about 3 inches deep and then we seeded it. I don't think it will grow in winter, grass typically needs weather around 60 degrees to grow, and it can grow when it is 50 (oh yeah, in Fahrenheit) but it grows very slowly. If you throw out fresh-ish manure sparely on the pasture, it may help, but big piles will just kill the grass. I haven't tried adding all the way composted manure on good grass, but my guess would be it would bury the grass under it. I would only put fully composted manure on a field, when it is dirt consistency. Hope I answered your question!