Germination temperature
Warm; a 2025 seed-quality study tested germination at 25 °C (77 °F).
Tree growing guide
Annatto is a warm-climate shrub or small tree grown for its red seed pigment and showy pink flowers and spiny pods. This guide covers the hard-seed problem, sowing depth for its long taproot, when to plant out and how to keep the pods clean.
Warm; a 2025 seed-quality study tested germination at 25 °C (77 °F).
At least 2.5 cm (1 in), because the seedling quickly sends down a long taproot.
Within about 20 days in laboratory tests; hard seeds can lag behind.
Seed is covered; grow seedlings and plants in a sunny position.
Fresh seed often germinates untreated; old or hard seed benefits from nicking the seed coat.
Usually raised in a nursery and planted out after about 4 months at 15-25 cm (6-10 in).
Annatto seed has intermediate storage behaviour. World Agroforestry reports that it tolerates drying to about 10% moisture and kept its viability for 12 months at 23 °C (73 °F), but drying to about 4% or freezing damages it, and germination of sun-dried seed fell to 12% after three years. Sow seed within its first year and do not keep it in a freezer.
Helpful for hard seeds. Brazilian researchers (Revista Brasileira de Sementes, 2002) traced low annatto germination to seed-coat dormancy, found more hard seeds among the heaviest seeds, and recommended mechanical scarification: rub each seed lightly on sandpaper or make a small nick in the coat, keeping the cut shallow.
Not needed. Annatto is a frost-tender tropical plant with no cold requirement.
Optional. Hot water is less reliable than scarification: in a 2025 study a 5-minute dip at up to 60 °C (140 °F) did not change germination, while 70 °C (158 °F) reduced it. A plain overnight soak in room-temperature water is a gentle alternative.
Keep the seed tray warm. In the 2025 study seeds were germinated at 25 °C (77 °F) and the untreated control reached 82%. In India, sow in the warm months; in cooler countries use a heated propagator or a warm windowsill.
World Agroforestry advises a minimum depth of 2.5 cm (1 in) because of the long taproot, with seeds 10 cm (4 in) apart in rows 25 cm (10 in) apart in nursery beds. In containers use deep pots or root trainers rather than shallow trays.
A well-drained mix. Annatto grows on most soils but prefers well-drained, neutral to slightly alkaline ground.
Keep evenly moist. Weed nursery beds often without disturbing the roots, and mulch if rain does not keep the soil damp.
Not needed for germination under a soil cover. Give seedlings bright light; the adult plant needs a sunny position.
In the 2025 study germinating seeds were counted daily up to day 20. Expect a spread of emergence: hard seeds can come up weeks after the rest, so do not discard a tray too early.
Plant out after about 4 months, when seedlings are 15-25 cm (6-10 in) tall (World Agroforestry). Lift with as much root as possible, shade new transplants for a few days against sun scorch, and plant at the start of the rainy season.
Keep young plants weeded and watered through the first dry season. Under good conditions fruiting starts about 18 months after planting or earlier, and full seed crops arrive after 3-4 years. Seed-grown plants flower later and less freely than plants grown from cuttings.
Cause: hard, water-impermeable seed coats, or old seed that has lost viability. Fix: scarify the remaining seed, sow fresher seed and give the tray more time.
Cause: Oidium bixae powdery mildew, which is worse on bristly pods that hold moisture. Fix: space plants for airflow, prune for an open crown and remove affected pods.
Cause: thrips (Selenothrips rubrocinctus can cause heavy damage). Fix: check the undersides of leaves, remove badly damaged shoots and keep plants well watered, since stressed plants suffer more.
Cause: sun scorch and root damage at transplanting. Fix: harden off gradually, keep the root ball intact and give temporary shade.
Cause: annatto needs a frost-free climate. Fix: in cold regions grow it in a large container under cover in winter.
World Agroforestry gives a mean annual temperature of 20-26 °C (68-79 °F) and 1,250-2,000 mm of rain spread through the year, up to 2,000 m altitude. Humid parts of India suit it; in dry areas water regularly.
Fruit matures 5-6 months after pollination. Pick capsules when they turn brown and start to split, dry them in the shade and rub out the seeds.
Light pruning after the main harvest keeps the plant compact and encourages new flowering shoots.
Annatto makes an attractive flowering screen; plant in a row at the start of the rains and trim lightly.
Sow annatto in warm weather for a flowering shrub with bright red seed pods.
Annatto has hard seed coats that keep part of each seed lot dormant. Nick or sand the coat, keep the tray warm and moist, and allow several weeks. Seed older than a year also loses viability.
Under favourable conditions the first fruit comes about 18 months after planting or earlier, with full crops after 3-4 years.
Yes, in a deep pot of free-draining mix in full sun. It is frost-tender, so bring it indoors where winters are cold.