Ocimum tenuiflorum aka Tulasi

Holy basil thrives in warm temperatures between 70-80°F (21-27°C), reflecting its tropical origins. It can tolerate a range of 15-35°C (59-95°F) but performs best at 20-28°C. The plant is frost-sensitive and does not tolerate temperatures below 32°F (0°C). When dormant, it may survive brief exposure to about -1°C, but prolonged cold will kill the plant. In cooler climates, bring plants indoors before the first frost.

Holy basil is not a heavy feeder and can grow in nutritionally poor soil. Avoid over-fertilizing, especially with high-nitrogen fertilizers, as this can reduce the essential oil content and medicinal properties of the leaves. Organic options like compost tea or fish emulsion work well for maintaining healthy growth.

Holy basil has a distinctive, complex aroma described as a mix of clove, mint, and basil with peppery undertones. The Krishna (purple-leaved) variety has a sharper, more pungent scent with strong clove notes, while Rama (green-leaved) has a milder, sweeter fragrance. Vana tulsi offers lemony, citrus notes. The leaves are highly aromatic and release their scent when touched or bruised. The fragrance intensifies when the plant flowers.

Yes, holy basil produces attractive flower spikes throughout summer. The small tubular flowers are white, pale pink, or light purple, arranged in compact clusters along terminal racemes that can reach 4-12 cm long. Flowers bloom from the base upward, each about 1.2 cm long. The flowering spikes are highly attractive to bees, butterflies, and hummingbirds. To extend leaf production, pinch off flower buds as they form; however, allowing some blooms supports pollinators and seed production.

Three main cultivated varieties exist: Rama tulsi (green leaves, mild sweet flavor, most common), Krishna tulsi (purple-green leaves, peppery with strong clove notes, considered most medicinal), and Vana tulsi (technically Ocimum gratissimum, wild forest variety with lemony scent, grows taller). Rama and Krishna are true Ocimum tenuiflorum, while Vana is a related species. Krishna's purple coloration comes from higher anthocyanin levels, providing additional antioxidant benefits.

Holy basil grows outdoors year-round as a perennial in USDA zones 10-12. In cooler zones (5-9), it can be grown as a summer annual, planted after the last frost when soil warms to 70°F. Choose a sunny location with at least 6-8 hours of direct sunlight and well-draining soil. Space plants 12-18 inches apart. The plant is heat-loving and thrives in hot summers but must be protected from or brought indoors before frost. In zones 9 and below, harvest before first frost or treat as an annual.

Regular pruning encourages bushier growth and extends the harvest period. Pinch off growing tips when plants reach 6 inches tall to promote branching. Remove flower buds as they appear to prolong leaf production—flowers signal the plant to stop producing new leaves. Harvest leaves by cutting stems just above a leaf node, which stimulates new growth. Prune dead or yellowing leaves promptly. After cutting, the plant regenerates quickly, allowing multiple harvests throughout the growing season.

Repot holy basil when roots emerge from drainage holes or growth slows despite proper care, typically annually for vigorous plants. Choose a container 1-2 inches larger than the current pot with good drainage. Use well-draining potting mix amended with perlite. Repot in spring when active growth resumes. Since holy basil is often grown as an annual, many gardeners start fresh plants from seed each year rather than repotting.

Holy basil propagates easily by seed or cuttings. For seeds, sow indoors 6-8 weeks before last frost in a light seed-starting mix. Seeds need light to germinate, so press them gently onto the surface without covering deeply. Keep moist at 70-75°F; germination takes 7-14 days. For cuttings, take 4-6 inch stems below a leaf node in spring or summer, remove lower leaves, and place in water or moist soil until roots develop (2-3 weeks). Division of established plants is also possible in early spring.

Yellow leaves on holy basil typically indicate overwatering, poor drainage, or nutrient deficiency. Check that soil drains well and reduce watering if soil stays soggy. Yellowing lower leaves with healthy new growth usually signals nitrogen deficiency—apply balanced fertilizer. Cold stress can also cause yellowing; ensure temperatures stay above 50°F. Root rot from waterlogged conditions turns leaves yellow before the plant wilts. Examine roots for brown, mushy tissue and repot in fresh, well-draining soil if rot is present.

Common pests include Japanese beetles (which skeletonize leaves), aphids, spider mites, whiteflies, and thrips. Hand-pick Japanese beetles into soapy water. For aphids and mites, spray with insecticidal soap or neem oil. Fungal diseases like downy mildew and powdery mildew occur in humid conditions—improve air circulation by proper spacing. Root rot develops in waterlogged soil; ensure good drainage. Holy basil is generally resilient, but prevention through proper spacing, good drainage, and avoiding overhead watering reduces most problems.

Holy basil is primarily pollinated by insects, particularly bees. Honeybees, bumblebees, and sweat bees are strongly attracted to the flowers, earning it the nickname 'bee candy.' Butterflies and hummingbirds also visit. The plant can self-pollinate, but cross-pollination by insects produces more vigorous offspring. If growing indoors or in areas with few pollinators, gently shake flowering stems or use a small brush to transfer pollen between flowers. Allow some plants to flower to support beneficial pollinators in your garden.

Yes, holy basil is highly edible with a rating of 4 out of 5 from PFAF. Leaves, flowers, and seeds are all edible. The leaves have a distinctive spicy flavor combining clove, mint, and basil notes—stronger than sweet basil. Unlike sweet basil, holy basil is typically used cooked rather than raw, as cooking mellows its intense flavor. It's popular in Thai cuisine (known as kra pao), teas, and Ayurvedic preparations. Fresh leaves can be added to stir-fries, curries, and soups. Dried leaves make excellent herbal tea.

Holy basil is one of the most important herbs in Ayurvedic medicine, earning a medicinal rating of 4 out of 5 from PFAF. Traditional uses include treating fevers, colds, respiratory conditions, inflammation, and blood sugar management. It is considered an adaptogen, helping the body cope with stress. Modern research supports antioxidant, anti-inflammatory, and blood sugar-regulating properties. Commonly consumed as tulsi tea for general wellness. WebMD notes it is 'possibly safe' for short-term use at 500mg daily. Consult healthcare providers before medicinal use.

Beyond culinary and medicinal applications, holy basil has several practical uses rated 2 out of 5 by PFAF. The plant acts as a natural insect repellent—its strong aroma deters mosquitoes and other pests. In Hindu tradition, stems are used to make prayer beads (mala). The essential oil is used in aromatherapy and natural perfumery. Holy basil is an excellent pollinator plant, attracting bees and butterflies to gardens. Its rapid growth and attractive foliage also make it suitable as an ornamental herb in containers and garden beds.