Try to aim for a seed spacing of at least
11.9 inches (30.5 cm) and sow at a depth of around
0.25 inches (0.635 cm). Soil temperature should be kept higher than
18°C / 64°F to ensure good germination.
By our calculations, you should look at sowing Dark Lilac Beauty about 49 days before your last frost date.
As Dark Lilac Beauty is hardy, ensure temperatures are mild enough to plant out - wait until after your last frost date to be on the safe side.