The Characteristics of Neem Trees
A native of India, the Neem tree is related to mahogany. A hardy and long-lived evergreen, Neem trees are, according to the non-profit organization Winrock International “a versatile multipurpose tree for urban regreening, agroforestry, fuelwood production and for a variety of other products, including biopesticides.” Whether used as a decorative landscape accent or houseplant or grown for their oil and bark, Neem trees are easy to grow and maintain.
Neem trees are fast-growing, medium-sized trees, usually attaining a height of 50 to 65 feet. Its trunk is short and straight with deeply fissured bark. The pinnate leaves are purple-red when young, developing to a medium green color when mature. The Neem tree produces small, fragrant white flowers and olive-like fruits.
The Neem tree is considered a tropical or semi-tropical tree, suitable for year-round outdoor growth in USDA zones 9 and 10. Neem trees prefer at least 30 inches of rainfall per year, but once established, they can withstand periods of prolonged drought, during which they may become completely leafless. Neem trees prefer full sun and a well-drained, sandy soil but will grow in less desirable soils.
The Neem tree protects itself from insect attack by producing chemicals known as limonoids. According to the National Academies Press, these “bioactive compounds are found throughout the tree, those in the seed kernels are the most concentrated and accessible.” These limonoids block insect growth and are effective against many serious agricultural and disease-causing pests.
Aside from its insecticidal properties, Neem oil has shown fungicidal and antibacterial properties as well. According to the Oregon State University Extension, “The Neem tree has been used medicinally in India for centuries…to inhibit allergic reactions and to inhibit plaque-forming bacteria. It has been used for skin infections and wounds as well as malaria and intestinal parasites in countries where it is native.”
The wood of the Neem tree is hard and durable. This, combined with its fast growth, makes Neem wood a viable timber crop. Neem tree plantations are being developed to exploit this versatile and valuable tree.
Pests and Problems
Neem trees are vulnerable to scale insects and young trees are subject to slug damage if they are overwatered. There are no known soil fungi or pathogens that attack Neem trees. In fact, under ideal conditions, hardy Neem trees can live up to 200 years.