The Neem tree is a member of the mahogany family, Meliaceae. It is known by its botanical name Azadirachta indica. Native to seasonally dry tropical woodlands in the Northeast of the Indian Sub-Continent, its exact origins are unclear.
It is thought by some to have originated in Assam and Burma where it is common throughout the dry Siwalik Hills. Some attribute it to the whole Indian sub-continent and others still to the whole of south and Southeast Asia.
Neem is most commonly utilized in India where it is grown in a variety of landscapes; from the southern tip of Kerala right up to the foothills of the Himalaya’s, throughout an area encompassing tropical to subtropical, semi-arid to wet-tropical, and from sea level right up to around 700 metres of elevation.
Neem trees are broadleaf evergreens capable of growing up to 30 metres tall with a girth of 2.5 metres. They can form rounded crowns from spreading branches as much as 20 metres across. They remain in leaf unless suffering from extreme drought.
The leaves are compound with toothed leaflets. The small fragrant white flowers are either staminate (male) or bisexual and are borne in clusters in the axils of the leaves. A sweet flavoured pulp is present in a smooth yellow/greenish drupe. Neem is usually grown from seeds but can be propagated from cuttings or root suckers.
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Neem roots penetrate the soil deeply allowing them to produce suckers. The taproot in young trees maybe twice as long as the tree itself. Neem will thrive just about anywhere in the lowland tropics but does best in areas with an annual rainfall of between 400 – 1200mm per annum. Capable of withstanding the harshest heat, they can endure temperatures in the shade surpassing 50 °C, yet cannot stand freezing or long periods of cold.
Neem responds well to both pollarding and being coppiced and regrowth can be exceptionally fast, due to its root system being large enough to sustain and feed a large tree.
With a rapid growth rate, Neem can be cut for timber after just 5- 7 years. It is capable of growing on dry and largely infertile grounds and performs well on stony and shallow land and where there is a hardpan near the surface. Neem cannot stand wet feet and quickly perishes if waterlogged.
Medicinal Uses
All parts of Neem have been used in Ayurvedic medicine as well as in organic farming applications for a very long time. Many of its multiple possible applications come from its potent antibacterial and antifungal properties. It is commonly used in shampoos for treating dandruff, and soaps and creams for ailments of the skin such as acne, athlete's foot, and psoriasis.
The leaves, bark, seeds, roots, and flowers are all used to make medicine. In the modern-day Indian sub-continent it’s also a common component in toothpaste and mouthwashes, following on from the tradition, still followed today by many, of using young twigs to clean one's teeth.
The leaves have long been used as a traditional treatment for diabetes and there is some preliminary clinical evidence suggesting it might help control blood sugar levels. They are also used for leprosy, eye disorders, blood thinning, intestinal worms, stomach issues, loss of appetite, fever, gingivitis, and liver problems, as well as birth control and to induce abortion.
The flower is used for the reduction of bile and phlegm and also is used against intestinal worms. The fruit is also used for intestinal worms, hemorrhoids, urinary tract disorders, phlegm, eye disorders, wounds, and leprosy. The stem, root bark, and fruit are used as a tonic and astringent.
Horticultural Uses.
Oil extracted from the seeds is most often used for pest control, being directly applied as an insect and mite repellent, as well as a fungicide and is the source of many organic commercial pesticide products.
Azadirachtin is the active insecticidal ingredient and disrupts the hormones involved in molting, preventing larvae from developing into adults and reproducing, as well as being a feeding inhibitor. Neem oil can kill soft-bodied insects and decrease mating.
As a fungicide, neem oil is used to treat and control rust, mildew anthracnose, blight, and scab. With low toxicity towards mammals, neem-based pesticides are popular in organic farming practices.
A neem tree will usually begin bearing fruit after 3-5 years and becomes fully productive after 10 years. From then on it can produce up to 50 kg of fruits annually. A neem tree may live for more than two hundred years.