Try to aim for a seed spacing of at least
11.7 inches (30.0 cm) and sow at a depth of around
0.0 inches (0.01 cm). Soil temperature should be kept higher than
65°C / 149°F to ensure good germination.
By our calculations, you should look at sowing Beckwith's Gem about 56 days before your last frost date.
As Beckwith's Gem is tender, ensure temperatures are mild enough to plant out - wait until after your last frost date to be on the safe side.