Tamarind bonsai

Placement

In the wild, tamarind is a full-sun tree that is frost-tender and cannot take cold, especially when young. As a bonsai in a temperate climate, it is therefore kept indoors for much of the year, in a room held between 59 °F and 84 °F. Avoid extremes: no cold shocks next to icy glass, and no dry heat above a radiator or in front of an air conditioner.

Light is its main need. A south-facing window is the best indoor spot: a few steps away from the glass, light levels drop sharply. Most bonsai need about four to six hours of direct sun; behind glass, though, shield the foliage from scorching midday sun, which can burn it. In winter, a grow light running about ten hours a day helps a great deal. A tray of damp gravel under the pot raises the humidity around the tree.

In the warm season it benefits from time outdoors. First place it in partial shade for two weeks to adjust, then in full light. Bring it back in before temperatures fall below 59 °F again.

Don’t worry if its leaflets close in the evening: this is natural behavior for the species, and they open again in the morning.

Soil mix

Use a well-draining bonsai mix that water passes through without pooling: once established, tamarind handles drought very well but dislikes waterlogged roots. A mix of half akadama, one-quarter pumice, and one-quarter lava rock suits broadleaf trees. If you cannot check the tree often, increase the share of akadama, which holds water; in a humid climate, add lava rock or grit. The pot needs drainage holes, and the saucer should be emptied after each watering.

Watering

Never water on a fixed schedule. Push a finger into the mix: when it is dry to about 1 in, water thoroughly until water runs from the drainage holes, then repeat a few minutes later to soak the whole root ball. Between 75 °F and 95 °F its needs rise sharply; below 50 °F they become low. Overwatering is more dangerous than underwatering, because it leads to root rot. Rainwater is ideal, but tap water is fine. Misting has only a passing effect on humidity.

Feeding: from spring through autumn, apply a balanced water-soluble fertilizer every two to four weeks at the manufacturer’s rate, then stop during winter. Do not feed right after repotting, while the roots recover.

Pruning

Prune regularly to keep a compact shape: remove dead, diseased, or crowded twigs, as well as shoots that grow out of the silhouette. An indoor tree can be pruned year-round; two to four maintenance prunings a year are usually enough. On a healthy tree, never remove more than one-third of the foliage at a time.

Structural pruning, which removes large branches, is done once a year in early spring. Choose main branches that are well spaced along the trunk. Use sharp concave cutters and cover large wounds with cut paste. After structural pruning, wait until the following spring to repot.

Work with its natural habit, with supple twigs that droop at the tips, and show off the gnarled trunk that gives it its charm.

Wiring

Wire young trees and young twigs, which are still flexible. These branches are delicate: bend them gently and remove the wire in time, before it marks the bark. Anodized aluminum wire suits broadleaf trees and beginners best. Choose wire about one-third the thickness of the branch, wound at 45°. Branches swell around the wire within one to four months: check them often and remove the wire by cutting it at every turn rather than unwinding it. For a thicker branch, a thin guy wire anchored to the pot and padded with a piece of rubber is a gentler alternative.

Repotting

Repot every two to three years in early spring, just before new growth begins. Prune the roots moderately, never removing more than one-third. A young plant forms a taproot, which is shortened when repotting. Afterward, the tree can take a season to fully recover.

Tamarind is easy to grow from seed: seeds taken from ripe fruit germinate about a week after sowing. Cover them with about 1 in of free-draining mix kept slightly moist and warm. Wait at least a year before repotting a seedling, and another year before pruning or wiring it. Semi-hardwood cuttings 2–4 in long root with warmth and humidity; air layering also works.

Watch for aphids, scale, and spider mites, and treat them with insecticidal soap or horticultural oil. Good air circulation limits leaf spot. Finally, the pulp of its pods is toxic to dogs: see the tamarind plant profile for precautions.