Aim to sow
0.51 inches (1.3 cm) deep and try to ensure a gap of at least
5.85 inches (15.0 cm). Soil temperature should be kept higher than
10°C / 50°F to ensure good germination.
By our calculations, you should look at sowing Premium Green about 42 days before your last frost date.
As Premium Green is tender, ensure temperatures are mild enough to plant out - wait until after your last frost date to be on the safe side.