Adansonia rubrostipa aka Fony Baobab

Adansonia rubrostipa is considered a challenging plant to grow, requiring specific conditions to thrive. The main difficulties include providing excellent drainage to prevent root rot, managing the dormancy period correctly (reducing water significantly in winter), and ensuring adequate warmth and light. Success depends on understanding its natural growing cycle—active growth during warm, moist periods and dormancy during cool, dry seasons.

The fony baobab is the smallest of the Malagasy baobab species, typically growing 4-5 meters tall in cultivation, though wild specimens can reach up to 20 meters. The characteristic bottle-shaped trunk can reach 2 meters in diameter. Growth is slow, and the tree develops an irregular, open crown. In containers, growth remains compact for many years, making it suitable for indoor cultivation when young.

Adansonia rubrostipa is endemic to western Madagascar, found nowhere else in the world. It grows in the dry deciduous forests and spiny thickets (spiny desert) of the region, from Baie de Baly National Park southward. The species thrives on well-drained calcareous soils and karstic limestone at elevations up to 500 meters, sometimes growing directly out of the distinctive tsingy limestone formations in areas like Anjajavy Forest.

Adansonia rubrostipa requires exceptionally well-draining soil to prevent root rot. A mix of half soil, half humus with added river sand works well. In its native habitat, it grows on sandy and limestone soils. The pH should be neutral to slightly alkaline (6.6-7.5), reflecting its preference for calcareous substrates. Rocky, mineral-rich substrates are preferred over rich organic soils.

As a tropical species from Madagascar, Adansonia rubrostipa requires warm temperatures and is hardy in USDA zones 9-11. It cannot tolerate frost and should be kept above 10°C (50°F) at all times. During the growing season, it thrives in warm to hot conditions. In cooler climates, it must be grown in containers and brought indoors during winter, where it will naturally enter dormancy.

Adansonia rubrostipa is adapted to arid conditions and does not require high humidity. In fact, high humidity combined with poor air circulation can promote fungal issues. Average household humidity is generally sufficient. During the dormant winter period, low humidity is actually beneficial as it mimics the dry season conditions of its native Madagascar habitat.

Baobabs have modest fertilizer requirements due to their adaptation to nutrient-poor soils. During the active growing season (spring through early fall), apply a balanced, diluted fertilizer monthly. Avoid fertilizing during dormancy when the plant sheds its leaves. Over-fertilizing can cause weak, leggy growth and may harm the plant. Organic fertilizers or slow-release formulations work well.

Adansonia rubrostipa follows a distinct seasonal cycle. During the warm growing season (typically spring to early autumn), water regularly when soil dries and provide full sun. From late summer or autumn, the tree naturally sheds its leaves and enters dormancy. During this period, keep the soil almost completely dry—only water sparingly if the trunk shows signs of severe shriveling. Resume regular watering when new growth appears in spring.

Yes, Adansonia rubrostipa produces striking flowers with bright yellow to orange-yellow petals. The flowers have a distinctive structure with a pale yellow staminal tube up to 10cm long bearing 100-150 filaments, with the inner filaments fused into a unique central bundle—an identifying feature of this species. Flowers typically open at night for pollination. However, flowering requires mature plants and may take many years to occur in cultivation.

Adansonia rubrostipa is primarily pollinated by fruit bats, with nocturnal hawk moths also playing a role. In Madagascar, fork-marked lemurs have been observed visiting baobab flowers to lick nectar, potentially contributing to pollination. The flowers open at night to attract these nocturnal pollinators. In cultivation outside Madagascar, hand pollination may be necessary if flowers are produced.

Seeds are the primary propagation method. The hard seed coat requires scarification—either carefully nicking with sandpaper or soaking in warm water for several days. Plant scarified seeds 1.5cm deep in a mix of half soil and half humus. Keep consistently moist and warm. Germination typically occurs within 1-2 weeks under good conditions but can be erratic.

Repot young plants annually in spring as growth resumes. Mature specimens can be repotted every 2-3 years or when roots fill the container. Choose pots only slightly larger than the previous one, as oversized containers retain excess moisture. Ensure excellent drainage with multiple drainage holes. Spring, just before active growth begins, is the ideal time for repotting.

Minimal pruning is typically needed. The tree naturally develops its characteristic bottle shape and irregular crown. Remove any dead or damaged branches in spring before new growth begins. Light shaping can be done if needed to control size in containers, but avoid heavy pruning as this can stress the plant. The slow growth rate means the tree maintains its shape well without intervention.

Yes, several parts of Adansonia rubrostipa are edible. The fruit pulp is consumed locally in Madagascar and sold in markets. The seeds contain approximately 11% oil composed of palmitic, oleic, and linoleic acids. Roots can be cooked and eaten as vegetables. These traditional food uses are similar to other baobab species, though A. digitata is more commonly cultivated for food production.

The spongy wood of Adansonia rubrostipa comprises concentric sheets of fiber used for thatching material in Madagascar. Trees are either felled or fire-killed to harvest these wood sheets, which are peeled and sun-dried. Bark fibers are extracted for rope-making, a traditional practice among indigenous Malagasy populations. The large hollow trunks can also serve as water storage.

Root rot is the primary concern, caused by overwatering or poor drainage—this is the most common cause of death in cultivated baobabs. Fungal issues can develop in overly humid conditions with poor air circulation. Spider mites may occasionally affect plants, especially in dry indoor environments. Scale insects and mealybugs can also occur. Regular inspection and maintaining proper growing conditions are the best prevention.

Adansonia rubrostipa can grow outdoors year-round only in USDA zones 9-11 where temperatures remain above freezing. It thrives in hot, dry climates similar to its native Madagascar habitat. In cooler regions, it must be grown in containers and moved indoors during winter. When grown outdoors, provide full sun and ensure soil drains exceptionally well. Once established, plants are very drought-tolerant.

Taxonomically, Adansonia rubrostipa is now considered a variety of Adansonia fony (as A. fony var. rubrostipa) according to Plants of the World Online. The parent species A. fony also includes the variety A. fony var. fony. In cultivation, plants are typically sold simply as Adansonia rubrostipa or fony baobab, without recognized cultivar distinctions. Some natural variation exists in trunk shape and bark coloration.