Ocimum gratissimum aka African Basil

Taxonomy ID: 5496

Ocimum gratissimum is an evergreen shrub in the mint family, Lamiaceae. Common names include tree basil, fever plant and clove basil. Its native range covers tropical Africa and parts of Asia. These include India, Sri Lanka, Nepal and much of Southeast Asia. It grows near lakes, in savannah, in upland forests and on disturbed ground. The species varies widely in form and scent.

This woody plant grows upright and makes many branches. In gardens, it reaches about 5–8 feet [1.5–2.5 metres] tall. Its spread reaches about 3–5 feet [1–1.5 metres]. Broader accounts report heights of roughly 1.6–10 feet [0.5–3 metres]. Plants take two to five years to reach full size. The green leaves have soft hairs when young. They lose some of this hair as they age. Some plants have purple stems, leaf veins and flowers. Others have pale stems and veins, with white flowers. The flower spikes also bear hairs, and insects pollinate them.

Grow this tropical basil in full sun with shelter. It prefers rich, light soil that drains well. RHS accepts several soil types, from clay to sand. It also lists acid, neutral and alkaline soils as suitable. Soil may stay moist, but it must drain well. In Britain, RHS advises growing it under glass. Its H1B rating allows outdoor growth during warm summer weather. The rating gives a temperature range of 50–59°F [10–15°C]. Raise new plants from seed or softwood cuttings. Routine pruning is not required.

The leaves serve as both a vegetable and a seasoning. Cooks boil them alone or mix them with other greens. They also use the leaves to make tea. Some forms smell of cloves, while others smell of thyme. People sometimes eat the seeds in India. The plant also supplies essential oil for commercial use. Its oil varies in makeup between forms. Traditional medicine uses its leaves and stems for many complaints. These recorded uses do not establish safe or effective treatments.

Its bushy, evergreen form suits a sheltered herb collection under glass. The scented growth also has value as an insect repellent. Despite that use, glasshouse pests can still attack it. RHS lists red spider mite and whitefly as possible problems. Grey mould may also affect the plant. Useful Tropical Plants reports no known hazards for the species. That report does not establish the safety of every preparation.

Common names

African Basil, East Indian Basil, Russian Basil, Scent Leaf, Lemon Basil, Clove Basil, Tree Basil

More information about African Basil

What temperature does Ocimum gratissimum prefer?

Ocimum gratissimum thrives in warm temperatures between 70-95°F (21-35°C) and does not tolerate frost. The plant grows naturally in subtropical to tropical climates with annual temperature ranges of 17-25°C lows and 27-36°C highs. In colder regions, it must be brought indoors or grown in a greenhouse during winter, or cultivated as an annual.

How should I fertilize Ocimum gratissimum?

Apply a balanced fertilizer with a 5-10-5 (N-P-K) ratio every 4-6 weeks during the growing season, or use organic compost every 1-2 months. Research shows that Ocimum gratissimum is sensitive to nitrogen levels and responds well to adequate nitrogen supplementation, particularly for essential oil production. For intensive cultivation, nitrogen doses higher than normally recommended can improve growth and oil content.

What does Ocimum gratissimum smell like?

Ocimum gratissimum has an intense aromatic fragrance that varies by chemotype. The most common forms have a strong clove scent (eugenol chemotype) or a thyme-like aroma (thymol chemotype), with some varieties showing hints of lemon-thyme or citral. All plant parts are strongly scented, making it popular for culinary use, essential oil production, and as an insect repellent.

Does Ocimum gratissimum flower?

🌸 Summer to early fall

Yes, Ocimum gratissimum produces small white to pale pink flowers on tall spikes during summer to early fall, with year-round flowering possible in tropical climates. Flowering typically occurs around 136 days after germination. The flowers attract pollinators including bees, butterflies, and moths. Many growers remove flower spikes to prolong the plant's productive life and encourage continued leaf production.

What varieties of Ocimum gratissimum are available?

Ocimum gratissimum has at least six distinct chemotypes characterized by their essential oil composition: eugenol (most economically important, 40-95%), thymol, citral, ethyl cinnamate, geraniol, and linalool. The eugenol and thymol types are the most common, historically classified as O. gratissimum forma caryophyllatum and forma graveolens respectively. These chemotypes differ in fragrance and flavor, ranging from clove-like to thyme-like aromas.

Can Ocimum gratissimum be grown outdoors?

🇺🇸 USDA 10-11 🇬🇧 UK Zone H1B

Ocimum gratissimum grows best outdoors in USDA hardiness zones 10-11 where it can be cultivated as a perennial shrub. In colder regions (zones 5-9), it must be grown as an annual or overwintered indoors, as it is not frost-hardy. The plant thrives in sub-humid to moderately humid subtropical and tropical climates with annual rainfall of 700-2000mm and requires full sun exposure with 6-8 hours of direct sunlight daily.

How should I prune Ocimum gratissimum?

Prune Ocimum gratissimum regularly throughout the growing season to maintain shape and encourage bushier growth. Remove dead or yellowing leaves and trim back leggy stems. Harvest by cutting stems above lateral nodes to promote side shoot development. For optimal essential oil content, harvest when the plant reaches 15cm tall or when 75% of branches start flowering. Remove flower spikes as they appear to prolong the plant's productive life and concentrate energy on leaf production.

When should I repot Ocimum gratissimum?

Repot Ocimum gratissimum every 1-2 years or when it outgrows its current container. Choose a pot at least 20cm (8 inches) in diameter with good drainage holes, using well-draining potting mix rich in organic matter. For container cultivation, use pots of 5-12 liters (1.5-3 gallons) to accommodate the plant's root system. The best time to repot is in spring before active growth begins.

How do I propagate Ocimum gratissimum?

Ocimum gratissimum is usually propagated from woody stem cuttings, as this method is more reliable than seeds which have very low germination rates (below 10%). For cuttings, take healthy stems from mature plants and root in water or soil - roots develop within approximately 28 days. Seeds can be sown uncovered in well-drained, moist soil at 20-25°C and need strong sunlight to germinate, taking 8-10 days with sowing to flowering occurring in 60-90 days.

What pests and diseases affect Ocimum gratissimum?

Ocimum gratissimum is relatively pest-resistant but may be affected by aphids, spider mites, whiteflies, and occasionally caterpillars. Fungal diseases including powdery mildew and downy mildew can occur in overly humid conditions or with poor air circulation. Prevention includes proper plant spacing, avoiding overwatering, ensuring good drainage, and maintaining adequate air circulation. Inspect plants regularly and use organic pest control methods when needed.

How is Ocimum gratissimum pollinated?

🐝 Insects

Ocimum gratissimum is pollinated by insects (entomophilous pollination) and attracts diverse pollinators including honeybees, butterflies, moths, and flies. The plant provides essential nectar and pollen and flowers profusely, making it excellent for bringing pollinators to the garden. While primarily cross-pollinated by insects, the plant likely has a mixed breeding system capable of both cross-pollination and some self-pollination.

Is Ocimum gratissimum edible?

🍎 Rating 3/5 🥗 Leaves, Flowers, Seeds

Yes, Ocimum gratissimum is edible with leaves, flowers, and seeds all being consumed. The leaves can be used fresh or dried as a culinary herb with clove or thyme flavor, cooked as a potherb (alone or mixed with other vegetables), or infused for tea. The delicate flowers add flavor to salads, and seeds are occasionally consumed in India. The lemon-thyme flavored varieties are particularly suited for salads and seasonings.

What are the medicinal uses of Ocimum gratissimum?

💊 Rating 3/5

Ocimum gratissimum is used in traditional medicine as an aromatic, stimulant, antispasmodic, and antiseptic herb. It treats colds, influenza, fevers, headaches, flatulence, diarrhea, parasitic infections, and respiratory problems internally, while externally it addresses rheumatism and lumbago. Research has demonstrated antimicrobial, antioxidant, anti-inflammatory, cardiovascular, glucose-lowering, antifungal, and hepatoprotective activities in vitro and animal models, though clinical data in humans is lacking.

What other uses does Ocimum gratissimum have?

🔧 Rating 2/5

Beyond culinary and medicinal applications, Ocimum gratissimum serves multiple purposes. The essential oil (0.8-1.2% yield) is used in perfumery and mosquito repellent formulations. The plant effectively repels insects and is valued for this property. Peeled twigs serve as traditional chewing sticks for oral hygiene in some cultures. It is sometimes cultivated as hedging and is an excellent pollinator plant for gardens.

How difficult is it to take care of African Basil

If you're looking for a plant that offers a moderate level of challenge, African Basil is a great choice to test your gardening skills.

What is the region of origin of African Basil

African Basil’s native range is Worldwide.

What are the water needs for African Basil

💧 Moist
African Basil should be watered regularly, allowing the soil to dry out between waterings.

What is the right soil for African Basil

pH: Acid to neutral Light to medium
African Basil loves a well-draining soil. Perlite and vermiculite help with drainage, while coco coir adds organic matter, so a good potting soil mix will have all three. You can improve store-bought soil by adding some perlite to it.

What is the sunlight requirement for African Basil

African Basil requires abundant, bright, and direct light to thrive. The best placement for this plant is within one foot of a window to ensure it receives enough light. If you live in an area with more extreme weather, such as hot summers or cold winters, you may need to adjust the placement of the plant accordingly. During hot summer months, it is important to place the plant away from full sun, as this can cause the leaves to yellow or burn. During cold winter months, it is best to move the plant closer to the window to take advantage of the extra light that can help it survive. By keeping an eye on the current weather in your area, you can make sure your East Indian Basil is always in the right place to thrive.

What's the right humidity for African Basil

The African Basil does not need extra humidity. Plants primarily absorb water through their root system, making soil watering the best way to provide humidity to your plants.

Is African Basil toxic to humans/pets?

African Basil is toxic to pets if ingested. We suggest keeping this plant out of reach if you have cats or dogs in the home.

More info:
Wikipedia • GBIF

Sources

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