Try to aim for a seed spacing of at least
1.95 inches (5.0 cm) and sow at a depth of around
0.2 inches (0.5 cm). Soil temperature should be kept higher than
18°C / 64°F to ensure good germination.
By our calculations, you should look at sowing Butan Commercial #8 about 38 days before your last frost date.
As Butan Commercial #8 is tender, ensure temperatures are mild enough to plant out - wait until after your last frost date to be on the safe side.