HerbBasil
Dark Opal Basil
Purple Basil
Dark Opal Basil commands attention with its richly purple, almost black foliage that creates dramatic contrast in edible landscapes and containers. Developed in the 1950s at the University of Connecticut, this striking heirloom brings bold licorice and mint aromas with hints of ginger and sweet tea to gardens in zones 4-10. Ready to harvest in just 65 days, plants grow into compact 12-24 inch bushes perfect for borders or pots.
Photo © True Leaf Market(https://www.trueleafmarket.com/products/basil-seeds-purple-dark-opal-organic)
Growing Conditions
USDA Zone
4-10
Sunlight
Full Sun
Water
High
Soil
Well-drained, Fertile Loam
Preferred Temp65-85°F
Growth Stats
24 in
Height
12 in
Width
PeriodAnnual
TypeBush
Spacing
10-12 inches apart
Plant Profile
Sunlight
Full Sun
Water
High
Zones
4-10
Size
24in H x 12in W
Growth
Annual
Care
High
Hover over chart points for details
Highlights
The deep burgundy leaves shimmer with metallic green undertones in bright light, making this basil as ornamental as it is flavorful. Its complex aroma blends licorice, mint, ginger, and sweet tea into something uniquely captivating. The compact bushy growth stays neat in containers while producing bright cerise flower spikes that attract beneficial pollinators. Unlike many ornamental basils, Dark Opal maintains good culinary value, especially when young leaves are harvested early in the season.
Common Uses
The burgundy leaves excel in purple pestos, marinara sauces, and vinegar infusions where their deep color creates visual drama. Fresh young leaves work beautifully as garnishes for cocktails and fruit beverages, while the anise-flavored sprigs and light pink flowers add both flavor and color to drinks. The leaves can be steeped into sweet teas that showcase their anthocyanin content, or dried for seasoning blends that benefit from their complex licorice and mint notes.
Growing Timeline
First Bloom
Late Spring
First Harvest
Early Summer
Last Harvest
Late Summer
Care Instructions
Start Indoors
Sow seeds 1/4 inch deep indoors 6-8 weeks before the last frost date. Maintain soil temperature at 70°F for optimal germination, which occurs in 5-10 days. Plant 4-6 seeds per cell or space 3-4 inches apart.
Transplant Outdoors
Transplant when seedlings have 3-4 sets of true leaves and all frost danger has passed. Harden off seedlings before transplanting to reduce shock.
Direct Sow
Direct sow after frost danger passes, planting seeds 1/4 inch deep with 2-3 seeds per inch in rows 18-24 inches apart. Firm soil over seeds for good contact.
Harvesting
Begin light harvesting once plants are established, preferably in early morning when temperatures are cooler and leaves are less likely to wilt. Harvest young leaves and shoots early in the season for the best flavor quality. Complete a full harvest just before plants start to flower by cutting the entire plant 4-6 inches above ground level to promote second growth.
Pruning
Pinch off the tallest growth regularly to prevent flowering and maintain tender leaf production. Remove the top several sets of leaves on each stem while leaving at least three sets on the lower portion to encourage bushier growth and continued production.
Growing Calendar
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Companion Planting
Ecology & Traits
Edible
Soil pH Range
6 – 7
Scientific Classification
Ocimum L.
Family
Lamiaceae
Genus
Ocimum
History & Origin
“Dark Opal Basil emerged from breeding work at the University of Connecticut during the 1950s, representing an era when ornamental food plants were gaining popularity in American gardens. This heirloom variety was developed to combine the visual drama of deep purple foliage with the aromatic qualities gardeners expected from basil, creating something that could serve double duty as both herb and landscape accent.”