Try to aim for a seed spacing of at least
11.7 inches (30.0 cm) and sow at a depth of around
0.25 inches (0.64 cm).
By our calculations, you should look at sowing Dark jewel mix about 21 days before your last frost date.
As Dark jewel mix is tender, ensure temperatures are mild enough to plant out - wait until after your last frost date to be on the safe side.