How to Grow Cardinal Basil
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Cardinal Basil
Ocimum basilicum var. purpurascens
herbCardinal basil is an ornamental and culinary herb variety distinguished by its deep purple-red foliage and vibrant magenta flowers. It offers the classic basil flavor with a slightly spicy, peppery undertone and grows as a bushy annual plant. The striking coloring makes it popular for both kitchen gardens and decorative landscape plantings.
When should you plant Cardinal Basil in your zone?
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Example Cardinal Basil timeline · Pittsburgh, PA (Zone 6b)
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Plant Cardinal 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 Cardinal Basil
Around Jun 6≈ 50 days after planting
Sample dates for Pittsburgh, PA. Sign up to get exact Cardinal Basil dates for your own zip code.
Growing Conditions
Soil
Growing Zones
Find your zone →Best in zones 9-11; grown as an annual in cooler climates or indoors
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Seedling
10-14 daysTiny seedlings emerge with cotyledons, developing first true leaves that already show purple coloration
Provide bright light (grow lights if indoors), keep soil moist but not soggy, maintain 70-75°F temperature, thin seedlings to prevent crowding
Vegetative
3-4 weeksPlant develops bushy growth with increasingly darker purple foliage, no flowers yet; multiple stems and leaves expand rapidly
Pinch off top two sets of leaves when plant reaches 6 inches tall to encourage bushiness, maintain consistent moisture and full sun, fertilize every 2-3 weeks with balanced fertilizer
Budding
2-3 weeksFlower buds form at stem tips, plant reaches mature height of 12-18 inches, foliage darkens further
Continue pinching buds if you want to extend leaf harvest and delay flowering, maintain fertilization schedule, ensure adequate sunlight for color development
Flowering
4-8 weeks (continuing if deadheaded)Tall spikes of vibrant magenta-purple flowers bloom above the foliage, plant may become less bushy as energy goes to flowering
Deadhead flowers to encourage continued leaf production if harvesting for culinary use, or leave flowers for ornamental display and pollinator attraction, maintain consistent watering
Seed Production & End of Season
2-3 weeks to seed maturityIf left to set seed, flowers mature into seed pods containing small black seeds; plant growth slows and foliage may yellow
Allow seed heads to dry on plant if you want to save seeds, harvest seeds before they shatter and fall, pull plant at season's end or when frost threatens in cool climates
Companion Planting
Plan your garden →Plant with:
Avoid planting near:
Common Pests
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Hand-pick in early morning, use row covers on young plants, apply neem oil or insecticidal soap if infestation is heavy
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Increase humidity by misting, spray with strong water stream, apply neem oil or horticultural oil, ensure good air circulation
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Use yellow sticky traps, spray with insecticidal soap or neem oil, reflective mulches can deter them
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Remove affected leaves, use blue sticky traps, spray with neem oil or spinosad, encourage beneficial predatory insects
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Use disease-resistant varieties if available, ensure excellent drainage, remove infected plants, avoid overhead watering, sterilize tools
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Improve air circulation, avoid wetting leaves, remove affected leaves, apply sulfur dust or copper fungicide if severe
Uses
Aromatic Seasoning & Pesto
CulinaryCardinal basil offers the classic sweet basil flavor with subtle spicy undertones, making it excellent for Italian dishes, pestos, pasta, and fresh salads. The ornamental purple color adds visual appeal to garnishes and plated dishes. [source]
Infusions & Beverages
CulinaryFresh leaves can be steeped into herbal teas, lemonades, and cocktails. The peppery character complements citrus and fruity beverages. [source]
Traditional Herbal Remedy
MedicinalLike other basil varieties, cardinal basil contains aromatic oils with potential anti-inflammatory, antioxidant, and antibacterial properties, traditionally used in Ayurvedic and folk medicine. [source]
Natural Insect Repellent
HouseholdThe strong aromatic oils in cardinal basil act as a natural deterrent for mosquitoes, flies, and other flying insects, making it valuable near seating areas or windows. [source]
Ornamental Garden Feature
CraftThe deep purple foliage and brilliant magenta flowers make cardinal basil a striking decorative plant for container gardens, borders, and mixed plantings, prized for visual interest in culinary herb gardens. [source]
This is not medical advice. LizPlants is not a medical resource. Always consult a qualified healthcare professional before using plants medicinally.
Harvest Tips
Pinch off leaf clusters and flower buds regularly starting when plant is 6-8 inches tall to encourage bushiness and extend harvest. For maximum leaf production, pinch off flower buds before they bloom. Harvest leaves in the morning after dew dries but before midday heat. Never remove more than one-third of the plant at one harvest. Leaves are best used fresh but can be dried or frozen. Continue harvesting until frost or plant decline.
Fun Facts
- 🌱 Cardinal basil gets its name from its deep crimson-purple color reminiscent of cardinal bird plumage and cardinal vestments.
- 🌱 All parts of cardinal basil—leaves, stems, and flowers—are edible and can be used in cooking, making it fully harvestable for both flavor and garnish.
- 🌱 Basil is mentioned in ancient texts as a sacred herb in Hindu and Greek cultures, with cardinal basil continuing this heritage as a valued ornamental and culinary variety.
Gardening Terms
New to gardening? Learn about terms used in this guide:
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