The Tamarind Bonsai: The Exotic Tree That Sleeps at Night

The Tamarind (Tamarindus indica) is a bonsai that immediately carries the imagination towards distant, warm lands. It is an evergreen tropical tree (often semi-deciduous in our climates) valued for its elegant feathery canopy made up of small pale green leaflets and for the rough, dark bark that gives it an aged look even when young. One of its magical traits is nyctinasty: at sunset its leaves fold and close up on themselves, as though the tree were going to sleep, only to open again at dawn.

Origin & species

Native to tropical Africa (but spread for millennia across India and Asia), it is the only species in the genus Tamarindus. It belongs to the Fabaceae family (legumes). In the wild it is an imposing tree producing the well-known brown pods with their sweet-and-sour flavour used in cooking. As a bonsai it is appreciated for its toughness and ease of cultivation, provided its temperature requirements are respected.

Position and microclimate

The Tamarind loves heat and light.
Summer: Place it outdoors in full sun. Direct light is essential to keep the leaves small and the internodes short. It does not fear scorching heat, in fact it enjoys it.
Winter: It is a tropical plant. If you live in northern or central Italy you must bring it indoors or into a heated greenhouse as soon as temperatures drop below 10-12°C. Choose a very bright spot, away from cold draughts.

Watering

Like many tropical plants, it wants a soil mix that stays fresh but never soggy.
Water generously when the surface of the substrate begins to dry. In summer it drinks a great deal.
Beware of dry air: If kept indoors in winter, the air from radiators is its enemy. Mist the foliage often with demineralised water, or use a tray with damp expanded clay to create a favourable microclimate.

Water quality

It tolerates tap water, but prefers water that is not excessively hard. If you notice white deposits on the leaves or on the soil, alternate with rainwater or distilled water to wash away the excess salts.

Substrate

It needs a free-draining soil that prevents waterlogging (lethal to the roots) while still holding the moisture it requires.

• Recommended mix: 50% Akadama, 30% pumice and 20% general-purpose soil mix or humus.
• The organic component matters in order to feed this vigorous plant and to stop the root ball from drying out too much.

Repotting

Carry it out in late spring (May-June), when night temperatures are steadily above 15-18°C.
The Tamarind has a vigorous taproot system. Repot young plants every 2 years. During repotting you can shorten the central taproot to encourage fine lateral roots, but do not be too drastic if the plant is not in perfect health.

Fertilizing

It is a plant that grows all year round if kept warm.
Feed from spring to autumn with solid organic fertilizer.
If you keep it indoors in the warmth during winter and it continues to grow (putting out new leaves), you can carry on feeding lightly with a liquid product once a month. If instead it goes into rest (dropping leaves or stopping), suspend feeding.

Flowering and fruiting

In the wild it produces yellow flowers streaked with red and then the edible pods.
As a bonsai it very rarely flowers, unless it is an old specimen grown in ideal conditions (a tropical greenhouse). Enjoy the beauty of the foliage and the bark.

Structural pruning

Major cuts are made in late spring, when the plant is in full growth.
The wood is hard yet brittle at the same time. Remove branches growing vertically or crossing the trunk. Always protect the cuts with cut paste; the Tamarind tends to draw back sap if the wound dries out too much.

Maintenance pruning

Trim back the new shoots that grow too long during the growing season.
This operation stimulates inner ramification and keeps the canopy compact. If a branch becomes too long, the leaves at its base will tend to drop, leaving it bare: cut it back short so it starts again from behind.

Pinching

Carried out on the soft shoots. When they have produced 4-6 pairs of leaves, shorten them to 1-2 pairs. This ongoing work is the secret to dense foliage pads and clouds of vegetation.

Wiring & bending

Young branches are flexible, but they lignify and become stiff very quickly.
Apply the wire in summer on branches that are still green/light brown. Check it every 3-4 weeks: the rough bark hides biting wire well, with the risk of deep scars if you forget about it.

Pests and diseases

• Red spider mite: Enemy number one indoors. If the leaves yellow and fall, check for tiny webs underneath.
• Scale insect: It hides on the branches and under the leaves.
• Root rot: Caused by overwatering and poorly draining soil. The leaves turn black and limp.

Winter & protection

As said, it does not tolerate frost.
It must absolutely be protected. If you live in the south in warm coastal areas it can stay outdoors in a sheltered spot, but in the north it is a plant for indoors or a warm greenhouse. If it loses all its leaves in winter after a cold snap or a dry spell, do not despair: reduce watering and wait for spring, as it will often flush out new growth from old wood.

Yearly calendar

• January-February: Bright position indoors, check for pests.
• March-April: Awakening, start light fertilizing.
• May-June: Move outdoors, repotting, pruning.
• July-August: Strong growth, plenty of water, pinching.
• September: Bring indoors (in the north) before the nights turn cool.
• October-December: Keep indoors, misting.

Useful products for this bonsai

• Akadama Hard Quality (ideal substrate)
• Hanagokoro organic fertilizer (balanced feed)
• Plastic drip tray (to create humidity with clay pebbles)
• Copper-coloured aluminium wire (for shaping the branches)
• Angled branch cutter (for clean cuts)
• Acaricide (against red spider mite indoors)

Frequently asked questions about the Tamarind

Why are the leaves closed during the day too?
If they close in sunlight, the plant is suffering: it is thirsty or has had a cold or heat shock. It is a defence mechanism to reduce transpiration. Check the soil straight away.

Can I keep it outdoors in winter if I cover it?
In the north, no, not even with horticultural fleece. If the temperature drops below zero, it dies. In the south, in positions sheltered from the wind, it may make it with fleece, but it will probably lose all its leaves.

Why is it losing the inner leaflets?
Lack of light. The Tamarind wants plenty of light. If the inner branches are in shade, the tree lets them dry out. Thin the canopy or turn the pot towards the light often.