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sweet basil (Ocimum basilicum)

Ocimum basilicum is an upright, aromatic, often highly branched herbaceous plant. Sources differ on its life cycle: it is commonly grown as an annual, while in warm, tropical, or Mediterranean-type climates it may be a short-lived perennial or biennial.

LightIt prefers full sun in a sunny, relatively sheltered position.
WaterThe soil should retain moderate moisture while remaining well drained; the roots need adequate water, and poor drainage should be avoided.
TemperatureTemperature figures come from a single source, which reports about 7 °C as a minimum, about 18–27 °C as an ideal range, and about 36 °C as a maximum.
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Overview

Ocimum basilicum is an upright, aromatic, often highly branched herbaceous plant. Sources differ on its life cycle: it is commonly grown as an annual, while in warm, tropical, or Mediterranean-type climates it may be a short-lived perennial or biennial.

Origin and habitat

Sources differ on the native range: it is mainly placed in tropical Asia, including the Indian subcontinent, southern China through Southeast Asia, the Malay Archipelago, the Philippines, and New Guinea, while some sources also include Africa and northern Australia. Long cultivation by people makes its original habitat unclear; it is also recorded from woodland, savanna, scrub, grassland, and human-made environments. It prefers warm tropical to subtropical climates, can also be grown as an annual in warm temperate climates, and does not tolerate frost.

Characteristics

Sources differ on mature height, giving a range of about 12–150 cm; a single source reports a mature spread of about 30–30 cm. The opposite leaves are usually green and ovate to ovate-lanceolate, though some cultivars have purple leaves; the surface may be glossy, the margins range from smooth to slightly toothed, and leaf size varies by cultivar. The small tubular or lipped flowers are mainly white but may be tinged pink or purple, and are borne in terminal spikes with stamens; flowering is mainly during a part of the year described by the RHS as late summer. A single source reports that the flowers are followed by small nut-like fruits that may be black.

Light

It prefers full sun in a sunny, relatively sheltered position.

Watering

The soil should retain moderate moisture while remaining well drained; the roots need adequate water, and poor drainage should be avoided.

Temperature and dormancy

Temperature figures come from a single source, which reports about 7 °C as a minimum, about 18–27 °C as an ideal range, and about 36 °C as a maximum.

Growing medium and mounting

It prefers fertile, relatively light, well-drained soil, including loam or sandy soil; a particular pH preference is reported, although it can tolerate a broader acidity-to-alkalinity range.

Propagation

It is propagated by seed, which can be sown indoors in warm conditions or directly outdoors in summer, and it is also readily transplanted.

Common problems

Potential pests include aphids, Japanese beetles, slugs, snails, and sage leafhoppers. It tolerates heat but is sensitive to cold and does not tolerate frost; in temperate regions it is usually grown as an annual.

Identification

A single source reports that the whole plant is aromatic, the stems are often square, and the leaves are opposite; aromatic compounds vary among cultivars and commonly include linalool, estragole, eucalyptol, and eugenol.

Photos

Ocimum basilicum
📷 user:Risacher · CC BY-SA 3.0 · source
Ocimum basilicum
📷 Castielli · CC BY-SA 3.0 · source
Ocimum basilicum
📷 no rights reserved, uploaded by 葉子 · CC0 · source

Sources