How to Grow Dark Opal Basil
Wikimedia Commons
Dark Opal Basil
Ocimum basilicum 'Dark Opal'
herbDark Opal is a striking purple-leafed basil variety with deep burgundy foliage and pink flowers, offering both ornamental and culinary appeal. It has a similar flavor profile to green basil with subtle peppery and slightly spicy notes. This cultivar is prized for its dramatic color in gardens and as a garnish.
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Example Dark Opal Basil timeline · Pittsburgh, PA (Zone 6b)
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Plant Dark Opal Basil
Around Apr 17Near Pittsburgh's average last spring frost.
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Tend & protect
Late spring–summerWatering, feeding, and pest-watch reminders.
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Harvest Dark Opal Basil
Around Jun 16≈ 60 days after planting
Sample dates for Pittsburgh, PA. Sign up to get exact Dark Opal Basil dates for your own zip code.
Growing Conditions
Soil
Growing Zones
Find your zone →Thrives in zones 5-10; grown as annual in colder zones 3-4
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Seedling
10-14 daysTiny seed leaves emerge, followed by true leaves with purple tinges. Plant is very delicate and small.
Keep soil warm (70-75°F) and consistently moist. Provide bright light indoors if starting from seed. Thin seedlings to proper spacing once they have 2-3 true leaves.
Vegetative Growth
3-4 weeksPurple leaves develop rapidly, stems thicken, and the plant becomes bushy. Foliage becomes darker purple as plant matures. Plant grows 12-18 inches tall.
Pinch off growing tips every 2-3 weeks to encourage bushiness. Remove any flower buds that appear. Maintain consistent watering and fertilize every 2-3 weeks with balanced fertilizer.
Flowering
2-4 weeksDistinctive pink to light purple flowers appear in terminal spikes. Flowers are attractive but reduce leaf quality and flavor if plant is grown primarily for leaves.
Pinch off flower buds if harvesting for culinary use to extend leaf production. Allow flowers to bloom if ornamental display is desired. Flowers are edible and attract pollinators.
Peak Harvest
4-8 weeksPlant is full and bushy with abundant dark purple foliage. Leaves are large, flavorful, and at peak color intensity.
Harvest regularly to maintain productivity and prevent flowering. Harvest from the top down, pinching off 2-3 leaf pairs at a time. Morning harvest yields best flavor.
Decline/Seed Set
Ongoing until frost or plant deathIf left unharvested, plant flowers prolifically, produces seeds in brown capsules, and leaf quality deteriorates.
Allow to flower if saving seeds. Collect seed capsules when they turn brown but before splitting. Deadhead regularly if extending harvest season is the goal.
Common Pests
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Hand-pick in early morning, use pheromone traps, apply neem oil or insecticidal soap
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Increase humidity, spray with water to dislodge, use neem oil or miticide for severe infestations
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Use yellow sticky traps, spray with insecticidal soap, increase air circulation
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Spray with strong water stream, use insecticidal soap, introduce ladybugs, apply neem oil
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Ensure well-draining soil, avoid overwatering, remove infected plants, practice crop rotation
Uses
Pesto & Pasta
CulinaryDark Opal basil makes an elegant purple pesto with a slightly more peppery flavor than traditional green basil pesto. Use fresh leaves in Italian dishes, pastas, and compound butters for a visually striking garnish. [source]
Garnish & Salads
CulinaryThe dramatic purple leaves add visual interest to salads, cocktails, and plated dishes. Use in vinaigrettes and fresh herb combinations for both flavor and aesthetic appeal. [source]
Herbal Tea & Infusions
MedicinalPurple basil leaves can be steeped into a mild herbal tea with antioxidant properties. Traditionally used in herbal medicine to support digestion and reduce inflammation. [source]
Garden Display & Containers
OrnamentalThe striking purple foliage and pink flowers make Dark Opal an excellent ornamental herb for containers, borders, and mixed garden beds. Popular in cottage gardens and contemporary herb displays. [source]
Edible Flowers & Arrangements
CraftThe delicate pink flowers are fully edible and add elegance to floral arrangements, wedding decorations, and plated desserts. Can be candied or used fresh as garnish. [source]
This is not medical advice. LizPlants is not a medical resource. Always consult a qualified healthcare professional before using plants medicinally.
Harvest Tips
Begin harvesting leaves when plant has 6-8 leaves and is 6 inches tall. Pinch off the top 2-3 leaf pairs regularly to encourage bushiness. Harvest in morning when leaves are most flavorful. Remove flower buds to extend leaf production. Plants can be harvested continuously until frost in cold climates or year-round in warm zones.
Fun Facts
- 🌱 Dark Opal was developed in 1962 by the University of Connecticut Agricultural Experiment Station and was the first purple basil variety developed in North America.
- 🌱 The purple color comes from anthocyanin pigments, the same compounds that give blueberries and red wine their color, and these have potent antioxidant properties.
- 🌱 Dark Opal basil flowers attract bees and other pollinators more readily than green basil varieties due to their more prominent coloration and extended flowering period.
Gardening Terms
New to gardening? Learn about terms used in this guide:
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