Winter (December through February)
The best season if you care about lawn damage. Turf is dormant, the ground is firm on most days, and the tracks of a mid size grinder barely mark the yard. Chips stay in the pile through winter, then start to break down once soil temperatures come up. The one caveat is a hard freeze morning after several sub-freezing nights, which we sometimes wait out for an hour so the top inch of soil thaws.
Spring (March through May)
Popular season and busy for us. The ground can be soft after heavy rain, which is when a big grinder leaves the worst ruts. If your yard drains slowly, we prefer to schedule the day after two dry days rather than the day after a storm. Spring is also the best time to seed a warm-season grass like bermuda over a fresh grind. If fescue is on your mind, wait until fall to seed even if we grind in spring.
Summer (June through August)
Fine for grinding, poor for seeding fescue afterward. Ground is dry, ruts are minimal, and the grinder moves at full speed. Chips decompose faster in summer heat but so does the exposed soil under them, which can bake into a hard cap if left uncovered. Water the spot lightly for the first two weeks and you avoid that.
Fall (September through November)
Our favorite season for a full grind and reseed cycle. Grind in early September, prep the spot, and seed fescue by mid October. Cool nights, warm days, and reliable rainfall give the new grass its best possible start. Chip decomposition is slower than summer but the trade is worth it because the spot is invisible by the following May.
What actually matters
Season is a soft preference. The three hard factors are yard access on the day (weather affects that), what you plan to plant afterward (fescue in fall, bermuda in late spring), and whether you have deep-freeze mornings when we should start after mid morning. Everything else is scheduling convenience. See how long after stump grinding can you plant grass for the seeding side of the calendar.