Also known as the kapok tree, the red silk cotton tree derives its name from the silken or cottony fibers within the fruit of the tree. Originating from the Asia, the tree is now grown in many tropical areas throughout the world, including Hawaii. Its large colorful blossoms are striking, making the silk cotton tree a desirable choice of the large specimen plant within the landscape.
The silk cotton tree is fast growing, putting on 4 to 6 feet of growth per year. Because the silk cotton tree is a tropical and subtropical plant, it is found primarily south of USDA hardiness zone 9. Flowering occurs for about a month, usually from February to March. Once flowering ends the plant will produce leaves.
Silk cotton trees frequently grow to over 80 feet high and 60 feet wide. The trunk of the tree can reach 10 feet around. It is upright, usually forming a single buttressed, leader trunk, which flares at the base. The tree forms a rounded and spreading crown with horizontal branches.
The bark of the tree is a light gray and may even appear white in bright sunlight. The tree also sports large, fat thorns along its branches which tend to lessen as the tree matures. The leaves are dark green and palm-like with five to seven leaflets radiating from a central stem. Each leaflet is lance-shaped, with smooth and wavy margins. Each leaflet is about 10 inches long. The flowers of the plant are most remarkable. They are bright orange to red in appearance with five large petals that are satiny in texture and multiple stamens projecting from the center of the flower. The fruit of the tree forms in the oval, woody capsules. When ripe these split open to reveal cottony fibers and small black seeds.
The trees grow best in rich, deep, and slightly acidic soils that drain well. Full sunlight is best, although the silk cotton tree will tolerate partial shade. Propagation is usually by plant seeds, growing out cuttings, or by air layering. The tree is relatively drought and fire tolerant, but low in salt tolerance.
The flowers of the silk cotton tree are fed upon by a range of wildlife, especially birds. The fibers are water resistant and can be used as stuffing or insulation. The wood of the tree is light and sturdy and is often used to make packing cases. The seeds provide an oil that can be used in soaps. In the United States, the silk cotton tree is grown primarily as a landscape specimen.