Keystone Resistant Giant
Sweet Bell Pepper in the US

Sweet bell peppers, being from the Solanaceae family, need a good start. You'll want to sow them indoors, around 6 to 8 weeks before your last frost date. Get them into good seed-starting mix, just a quarter-inch deep, maybe two seeds per cell, then thin to the strongest. They like it warm, around 70-80°F (21-27°C) for germination, so a heat mat really helps. For folks in zones 3 and 4, you're looking at May/June or June/July, while warmer zones can start much earlier, even January.

Once your seedlings have a couple of true leaves, prick them out into individual 3-4 inch pots. Keep 'em warm and in a sunny spot, or under grow lights, so they don't get leggy. Before planting out, harden them off properly for a week or two, gradually getting them used to the outdoors. Don't rush it; wait until all danger of frost is gone and the soil has warmed up nice and proper. Space them about 18-24 inches apart in the ground, or one per large container, and be ready to give them some support as they grow.