White Acorn
Acorn Squash (Pumpkin) in the US

You can sow acorn squash seeds indoors or direct, depending on your zone and when your last frost is. If you're starting indoors, get them going 2 to 4 weeks before that last frost, planting them about an inch deep in small pots. Keep them warm, around 70°F (21°C), on a windowsill or in a greenhouse. For direct sowing, wait until the soil's properly warmed up, usually after your last frost date, and sow seeds an inch deep, 2 to 3 feet apart in mounds. Like I say, check your zone, but generally, you're looking at March to May for zones 8 and 9, and May for zone 5.

Once your indoor seedlings have their true leaves, carefully prick them out if they're crowded, though I often just sow one seed per pot to avoid that faff. Before planting them out, you'll need to harden them off for a week or so, just getting them used to the outside world. Plant them out after all danger of frost has passed, giving them plenty of room, about 3 to 6 feet between plants. They're big spreaders, you know, so don't skimp on the space.