Sow
0.99 inches (2.54 cm) deep with a guideline distance of
2.97 inches (7.62 cm). Soil temperature should be kept higher than
4°C / 39°F to ensure good germination.
By our calculations, you should look at sowing Dark Green Perfection about 35 days before your last frost date.
As Dark Green Perfection is half hardy, ensure temperatures are mild enough to plant out - wait until after your last frost date to be on the safe side.