Sow at a depth of approx.
0.12 inches (0.3 cm) and aim for a distance of at least
1.17 inches (3.0 cm) between Horned violet plants.
By our calculations, you should look at sowing Columbine about 90 days before your last frost date.
As Columbine is hardy, ensure temperatures are mild enough to plant out - wait until after your last frost date to be on the safe side.