How to Grow Purple Thai Basil
Wikimedia Commons
Purple Thai Basil
Ocimum basilicum var. thyrsiflora
herbPurple Thai basil is an aromatic herb with deep purple stems and foliage, distinctly different from sweet basil. It has a complex flavor profile combining anise, licorice, and subtle spicy notes, making it essential in Southeast Asian cuisine. The plant produces attractive purple flower spikes and is highly ornamental as well as culinary.
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Example Purple Thai Basil timeline · Pittsburgh, PA (Zone 6b)
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Plant Purple Thai 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 Purple Thai Basil
Around Jun 16≈ 60 days after planting
Sample dates for Pittsburgh, PA. Sign up to get exact Purple Thai Basil dates for your own zip code.
Growing Conditions
Soil
Growing Zones
Find your zone →Thrives in zones 10-11; grow as annual in cooler zones or in containers brought indoors
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Seedling
2-3 weeksTiny plants with first true leaves emerging; delicate purple-tinged cotyledons visible
Keep soil moist but not soggy; provide bright light; maintain 70-75°F for best germination; thin seedlings to proper spacing after 2-3 true leaves develop
Vegetative Growth
4-6 weeksPlant develops multiple stems and leaves with deepening purple coloration; bushy habit forming
Pinch off top growing tips every 2-3 weeks to encourage bushiness; remove any flower buds that form to redirect energy to leaf production; maintain consistent moisture and full sun
Pre-flowering
2-3 weeksPlant reaches mature size with dense foliage; purple coloration fully developed; flower buds begin to form at stem tips
Continue pinching if leafy harvest is priority; reduce nitrogen fertilizer to encourage flowering if ornamental use is desired; maintain regular watering
Flowering
3-4 weeksAttractive purple flower spikes emerge above foliage; small tubular flowers attract pollinators
Harvest leaves regularly before flowers fully open for best flavor; deadhead spent flowers to encourage continued leaf production; provide balanced fertilizer
Late Season/Seed Development
Until frost or end of seasonFlowers mature and set seed; plant becomes woody if left unpruned; growth slows in cooler seasons
Allow some flowers to mature if saving seeds; harvest seeds once flower spikes brown and dry; in cooler zones, bring containers indoors before first frost
Companion Planting
Plan your garden →Plant with:
Avoid planting near:
Common Pests
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Hand-pick in early morning; use neem oil spray; encourage beneficial insects like parasitic wasps
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Increase humidity and misting; spray with water to dislodge; use neem oil or insecticidal soap if severe
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Use yellow sticky traps; spray with insecticidal soap; vacuum small infestations off leaves
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Spray with strong water stream; apply neem oil or insecticidal soap; attract ladybugs and lacewings
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Improve air circulation; avoid overhead watering; apply sulfur dust or baking soda spray (1 tbsp per gallon water)
Uses
Thai & Southeast Asian Cuisine
CulinaryPurple Thai basil is essential in Thai curries, stir-fries, and traditional dishes like Pad Krapow (Thai basil pork). Its anise and licorice notes add authentic depth to Vietnamese pho, coconut-based curries, and spicy Asian noodle dishes. [source]
Flavor Enhancement
CulinaryUse fresh leaves and flowers as a garnish for Asian soups, salads, and cocktails. The flowers are edible, ornamental, and add subtle anise flavor to dishes and beverages. [source]
Herbal Wellness
MedicinalPurple Thai basil contains eugenol and other compounds traditionally used in Southeast Asian medicine for digestive support, anti-inflammatory benefits, and as a natural antimicrobial. Brew leaves as tea for potential digestive and respiratory support. [source]
Garden & Container Display
OrnamentalThe striking deep purple stems and flowers make Purple Thai basil an attractive ornamental plant for containers, herb gardens, and mixed borders. It's particularly striking in summer and pairs well with other colorful herbs. [source]
Natural Fragrance
HouseholdFresh or dried Purple Thai basil can be used in dried herb bundles, sachets, and arrangements for its distinctive aromatic qualities. The dried leaves retain their fragrance and can be used to infuse oils. [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 6-8 weeks after planting once plant has 6-8 true leaves. Pinch off top 2-3 leaf pairs regularly to encourage branching. Harvest in the morning after dew dries for strongest aroma and flavor. Pick leaves and flower buds just before flowers fully open—they have the most intense flavor at this stage. Purple Thai basil is at its peak flavor in summer and early fall. In warm climates, you can harvest continuously through the season; in cooler zones, harvest aggressively before first frost.
Fun Facts
- 🌱 Purple Thai basil has been cultivated in Thailand and Southeast Asia for centuries and holds cultural significance in traditional cooking and herbal medicine practices.
- 🌱 The deep purple color comes from anthocyanin pigments, the same compounds found in blueberries and red wine, which increase in intensity with more sunlight exposure.
- 🌱 Unlike sweet basil, Purple Thai basil is more heat-loving and can actually thrive better in extremely hot, humid conditions typical of tropical climates.
Gardening Terms
New to gardening? Learn about terms used in this guide:
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