Fertilizing
Feed only while the tree is in leaf and growing. Use a liquid fertilizer at half strength, about once a month, from late spring to late summer.
- Stop feeding in autumn, once the leaves start to yellow.
- Do not feed a leafless, dormant tree or one that was repotted in the last month.
- Stronger doses easily burn the fleshy roots, so keep it light.
Placement
The baobab needs heat and as much sun as possible. Give it at least six hours of direct sun a day; outdoors in summer, in full sun, is ideal.
- Bring it indoors before night temperatures drop below 12°C (54°F), and move it back out only when nights stay above that.
- Indoors, choose the sunniest window or add a strong grow light, and keep it away from cold drafts.
- A dormant, leafless tree needs warmth (ideally 15–20°C, 59–68°F) more than light.
Pruning
Prune in the growing season, from late spring to midsummer, when the tree is in leaf and heals quickly. Trim elongating shoots back to one or two leaves to keep the shape and build ramification.
Thin branches tend to die back from cuts, so leave a short stub and remove it later once it has dried. Prune sparingly and avoid heavy cuts on a leafless tree. Shape mainly with scissors; young branches can be wired lightly, but watch the soft bark closely.
Repotting
Repot every 2–3 years in late spring, once temperatures are warm and new leaves are appearing. Never repot a dormant tree in the cold.
- Use a very gritty, fast-draining mix, such as pumice, lava rock and coarse sand with only a little organic matter; a pH around neutral (6–7) is fine.
- Remove no more than about a third of the root mass and let cut roots dry for a day or two before watering.
- A fairly deep pot helps the thick roots and stable growth.
Watering
The swollen trunk stores water, so the baobab tolerates drought well but rots easily in wet soil. Water thoroughly, then let the soil dry out almost completely before watering again.
- In summer heat and full sun, that can mean watering every few days.
- In cool or rainy weather, water much less.
- During winter dormancy, keep the tree warm and nearly dry: give only a small amount of water every few weeks so the roots do not shrivel.
Seasonal care
- Spring: When temperatures rise and new leaves appear, resume watering gradually and repot if due. Move the tree outside only once nights stay above 12°C (54°F).
- Summer: This is the main growing season: give full sun, warmth, monthly half-strength feeding, and water whenever the soil has dried out. Trim elongating shoots and do any structural pruning now.
- Autumn: As days shorten, the leaves yellow and drop; this is normal. Stop fertilizing, cut back on water and bring the tree indoors before temperatures fall below 12°C (54°F).
- Winter: Keep the leafless tree warm, ideally 15–20°C (59–68°F), and nearly dry while it is dormant. Cold combined with damp soil is the most common cause of losing a baobab.
Common problems
Most problems with baobab bonsai come from too much water or too little warmth.
- Soft, wrinkled or rotting trunk: Root rot caused by overwatering, especially in cool conditions. Unpot, cut away mushy roots, let the tree dry out and replant in a very gritty, fast-draining mix.
- Sudden leaf drop in summer: Usually a cold draft, low light or a drop below 12°C (54°F). Move the tree somewhere warmer and brighter; it will releaf once conditions improve.
- Spider mites and mealybugs: Common indoors in dry, warm air. Check leaf undersides and leaf axils, rinse the foliage and treat with a suitable insecticidal soap or oil.
- Branch die-back after pruning: Thin branches often die back from cuts. Prune in the growing season, leave a short stub and avoid removing many branches at once.
- Long, weak shoots: Too little light, typically indoors. Provide at least six hours of direct sun or a strong grow light.