Germination temperature
Warm, tropical conditions; protect from cold.
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Big-leaf mahogany and West Indian mahogany are tall tropical timber trees that grow easily from fresh winged seed. This guide covers both species, how they differ, shallow sowing straight into deep bags, and how to deal with the Hypsipyla shoot borer.
Warm, tropical conditions; protect from cold.
Shallow: about 1-2 cm (0.4-0.8 in); deep sowing fails.
Starts after about 1-2.5 weeks; complete in about 30 days.
Light shade during germination, then full sun.
None needed for fresh seed; break off most of the wing.
Sow directly into deep bags; plant out after 6-12 months at the start of the rains.
Sow seed as fresh as possible. Its storage behaviour is disputed: older work called it recalcitrant, World Agroforestry calls big-leaf seed 'probably intermediate', and the RNGR nursery protocol calls it orthodox. All agree it does not keep at room temperature: big-leaf seed lost most germination within 3-4 months and almost all within 6 months, and West Indian seed behaves the same way. For keeping longer, dry it and store it sealed in a refrigerator at about 4 °C (39 °F).
Not needed. Break off most of the papery wing so the seed fits the pot, without damaging the seed itself.
Not needed. Mahogany is tropical and has no cold requirement.
Not needed. USDA and the RNGR protocol use no pretreatment because fresh seed germinates well; some growers soak for 24 hours at room temperature, which does no harm.
Warm. No single optimum is published for home growers; big-leaf mahogany grows where mean annual temperatures are about 20-28 °C (68-82 °F). In India sow in the warm pre-monsoon months; in cooler countries use a heated propagator or greenhouse.
About 1-2 cm (0.4-0.8 in) deep (RNGR), or push the seed in edgewise with half of it showing (USDA). Do not bury it deeply: in a Brazilian test big-leaf seedlings sown 6 cm (2.4 in) deep failed to reach the surface. Orientation makes little difference.
Sow straight into deep bags or pots, one seed each; seedlings raised in beds and transplanted often develop a bent J-shaped taproot. The RNGR protocol uses bags about 6-12 cm (2.5-5 in) wide and 20 cm (8 in) deep filled with a soil-based mix; heavily composted or manure-rich mixes caused yellowing and stunting.
Keep evenly moist. Overwatering combined with heavy shade led to stem rot and damping-off in Asian nurseries.
Give light shade during germination, then remove it gradually once two pairs of leaves have formed; grow seedlings in full sun during active growth (RNGR).
USDA gives a start after 12-18 days and completion in about 30 days, with 39-98% germination for fresh lots; the RNGR protocol gives a start after 1-2 weeks and about 80% for fresh big-leaf seed.
Plant out at the start of the rainy season. Big-leaf seedlings are ready after 6-9 months, West Indian after about a year (USDA). Reduce watering for a month beforehand to harden them, water well before moving, and plant only vigorous seedlings with a woody stem base (RNGR).
Young trees need overhead light with some side shelter (World Agroforestry). Do not hold seedlings over to a second season in the bag, as roots coil.
Cause: the mahogany shoot borer, Hypsipyla robusta in Asia including India and H. grandella in the Americas. Its larvae tunnel into the young leading shoot, so the tree forks and the trunk is crooked. It is the most serious pest of mahogany. Fix: check young trees often during flushes, cut out attacked shoots and keep one strong new leader. Shade and mixed planting have been tried to reduce attack, but the evidence is conflicting (Hauxwell et al.).
Cause: old seed or deep sowing. Fix: use fresh seed and sow no deeper than 2 cm.
Cause: damping-off and stem rot, or stem-boring ambrosia beetles in the nursery. Fix: water less, increase light and air, and remove affected plants.
Cause: leaf blight and leaf spot fungi. Fix: space bags apart and avoid wetting foliage late in the day.
The faster, larger tree, native from Mexico to Amazonia. Its seed is big, about 1,300-2,400 seeds per kg. It needs about 1,600-2,500 mm of rain and grows best on well-drained medium to heavy soils (World Agroforestry); nursery plants are ready in 6-9 months (USDA).
A smaller, slower Caribbean tree with smaller seed: USDA gives 5,400-7,800 seeds per kg, World Agroforestry 3,350-3,500. It tolerates lower rainfall, from about 800 mm, and thrives on deep, well-drained sandy soils but not stiff clay. Nursery plants take about a year (USDA).
The two species hybridise freely where they grow together (World Agroforestry), so seed collected from mixed plantings may be a cross.
Both become large trees; plantations start at about 10 x 3 m (33 x 10 ft) and are thinned later.
Big-leaf mahogany starts fruiting regularly at about 15 years; West Indian usually at 30-40 years (World Agroforestry).
Sow fresh mahogany seed shallowly in deep bags for strong, straight-rooted timber trees.
Big-leaf mahogany grows faster and needs high rainfall; West Indian mahogany is smaller and slower but tolerates drier, sandy sites.
Only a few months at room temperature; germination drops sharply after 3-4 months. Sow promptly or store dry, sealed seed in a refrigerator.
Break most of the wing off so the seed fits the pot, then sow 1-2 cm deep. Which way it points makes little difference.
Inspect young trees during each flush of growth, prune out attacked shoots and train one new leader. No single method prevents attack completely.