Aim to sow
0.78 inches (2.0 cm) deep and try to ensure a gap of at least
5.85 inches (15.0 cm). Soil temperature should be kept higher than
13°C / 55°F to ensure good germination.
By our calculations, you should look at sowing Detroit 2 Bolivar about 14 days before your last frost date.
As Detroit 2 Bolivar is half hardy, ensure temperatures are mild enough to plant out - wait until after your last frost date to be on the safe side.