120 seeds. 60-90 Days. Ocimum basilicum purpurascens. Annual.
 
Basil 'Dark Opal' has beautiful, dark purple foliage with a deep flavor. The dark color comes from the high anthocyanin levels in the leaves of this attractive basil. This 1950s open-pollinated variety is prized for flavoring vinegar and for its ornamental color for garden borders. 
 
Height 16 inches.
 
Sowing Basil Seeds: 
 
Sow basil indoors 6 weeks before the last frost date, 1/8 inch deep. Transplant 2 weeks after the last frost date. Or direct sow outside after there is no chance of frost. Thin to 10 inches apart. Full sun.
 
Photo courtesy of Diane's Flower Seeds