How to Grow Opal Basil
Wikimedia Commons
Opal Basil
Ocimum basilicum var. purpurascens
herbOpal basil is a striking purple-leafed variety of sweet basil with a slightly spicy, clove-like flavor and ornamental appeal. The deep purple foliage and delicate pink flowers make it both a culinary and decorative garden plant. It's slightly hardier and more pest-resistant than green basil varieties.
When should you plant Opal Basil in your zone?
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Example Opal Basil timeline · Pittsburgh, PA (Zone 6b)
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Plant 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 Opal Basil
Around Jun 16≈ 60 days after planting
Sample dates for Pittsburgh, PA. Sign up to get exact Opal Basil dates for your own zip code.
Growing Conditions
Soil
Growing Zones
Find your zone →Best in zones 5-10; grown as annual in zones 2-4
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Seedling
2-3 weeksTiny purple-tinged cotyledons emerge, followed by first true leaves with characteristic basil shape and deep purple coloration
Keep soil warm (70-75°F) and consistently moist; provide bright light to prevent leggy growth; thin seedlings to proper spacing once 2-3 true leaves appear
Vegetative
3-4 weeksPlant develops bushy growth with multiple stems and increasingly deep purple oval leaves; plant is fully purple throughout
Pinch off terminal buds weekly to encourage branching and bushier form; ensure adequate light; begin light harvesting of outer leaves once plant has 4-6 leaf sets
Pre-flowering
1-2 weeksUpper growth begins forming flower buds; leaves may slightly reduce in size as plant transitions to reproductive phase
Continue pinching buds if extending vegetative growth is desired; reduce nitrogen fertilizer to slow flowering; increase water slightly during hot periods
Flowering
3-4 weeks (staggered if buds continually pinched)Delicate pink or white flower spikes emerge from purple foliage, creating striking ornamental effect; flowers are fully formed and attractive
Harvest flowers for culinary or ornamental use; deadhead spent flowers to extend plant life and promote continued leaf production; flowers are edible with spicy basil flavor
Seed Development & Decline
2-3 weeksFlowers fade and form seed pods; plant energy shifts to seed production; foliage quality declines, leaf flavor becomes more bitter
Allow selected flowers to remain for seed saving if desired; otherwise remove flowers to redirect energy to foliage; plant may begin to decline in cooler weather
Common Pests
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Hand-pick early morning; use row covers on young plants; spray neem oil in early morning or evening
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Spray with strong water jet; use yellow sticky traps; apply insecticidal soap or neem oil every 5-7 days
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Increase humidity; spray water on undersides of leaves; use miticide or neem oil if severe
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Remove affected leaves; use blue sticky traps; spray neem oil or insecticidal soap
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Choose resistant varieties; avoid overhead watering; improve soil drainage; remove infected plants immediately
Uses
Gourmet Garnish & Infusions
CulinaryOpal basil adds striking visual appeal as a garnish for desserts, cocktails, and plated dishes. Its flowers and leaves can infuse vinegars, oils, and syrups with spicy-clove basil notes. The color remains vivid even when dried. [source]
Purple Pesto & Sauces
CulinaryCreates a vibrant purple pesto with an elegant, slightly deeper flavor than green basil. Can be used in pasta dishes, as a spread, or mixed into cream-based sauces for sophisticated purple colorization. [source]
Anti-inflammatory & Antioxidant Properties
MedicinalContains polyphenolic compounds and anthocyanins (the pigment giving it purple color) with documented anti-inflammatory and antioxidant effects. Traditionally brewed as tea to support digestion and reduce inflammation. [source]
Garden Color & Border Planting
OrnamentalThe deep purple foliage with pink flowers provides striking color contrast in gardens and containers. Often used in ornamental herb gardens, mixed borders, and butterfly gardens. [source]
Natural Pest Deterrent
HouseholdThe plant's essential oils naturally repel certain insects including flies and mosquitoes. Growing near patios or entry points can help create a more comfortable outdoor space. [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 once plant has 6+ sets of true leaves. Pinch off terminal buds to harvest and encourage branching. Harvest in morning after dew dries for best flavor. Remove outer leaves regularly to keep plant productive. For flowers, pick when fully open and use fresh. Continue harvesting until first frost or plant decline. Never remove more than 1/3 of plant at once.
Fun Facts
- 🌱 Opal basil's purple color comes from anthocyanins, the same powerful antioxidants found in blueberries and red wine, making it more nutritionally dense than green basil varieties.
- 🌱 In ancient Rome, basil was used in love spells and courtship rituals—a purple basil plant given as a gift traditionally symbolized deep affection.
- 🌱 Opal basil is notably more cold-tolerant and pest-resistant than most green basil varieties, making it a better choice for variable climates and organic gardens.
Gardening Terms
New to gardening? Learn about terms used in this guide:
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