Germination temperature
Warm, tropical conditions; sow in the hot or rainy season, or indoors with heat.
Visit deodar-seeds.in Tree growing guide
Gulmohar, also called royal poinciana or flame tree, has hard seed that will not sprout until its coat is broken. Nick or hot-water treat the seed, sow it warm, and a young tree can flower in three to five years on a good site.
Warm, tropical conditions; sow in the hot or rainy season, or indoors with heat.
Shallow: cover with about the seed's own thickness of mix.
Scarified seed sprouts unevenly over several weeks.
Full sun.
Essential: nick, sand or hot-water treat the seed coat.
Sow in polybags or pots; plant out at 3-6 months.
Use plump, sound seed. Dry seed stores well at room temperature: in one test, seed kept 12 months at 26 °C (79 °F) still germinated at 60%, and TNAU gives about two years of viability. There are about 2,000-4,500 seeds per kilogram.
Essential. The seed coat is waterproof, and untreated seed lies dormant. Nick the coat with nail clippers or rub it on sandpaper on the side away from the scar where the seed was attached, until the pale inner layer shows. Alternatively pour boiled water over the seed and let it cool for about two hours (TNAU), or dip it in water at 90 °C (194 °F) for 10 seconds (USDA). Every published treatment beat untreated seed.
Not needed. It is a tropical tree; cold does not break its dormancy.
After nicking or the hot-water dip, soak the seed in room-temperature water for 24 hours. Sow the seeds that have swollen; nick again any that are still hard.
Keep the seed warm. On the Indian plains sow in the hot season or early rains. In temperate climates sow indoors with bottom heat or in a warm greenhouse, as the tree is grown only in frost-free areas.
Press swollen seed into the mix on its side and cover it shallowly, about the seed's own thickness.
Free-draining potting mix, or red soil with well-rotted manure in polybags, as Indian forest nurseries use. You can sow straight into polybags or in a seed bed and move the seedlings into bags.
Keep the mix moist but not wet; swollen seed rots in waterlogged compost.
Not needed for germination; move seedlings into bright light or full sun as soon as they appear.
Uneven. In a USDA report fresh, scarified seed reached 76% germination after nine weeks, so leave pots in place for at least two months.
Seedlings grow fast. TNAU moves them into large 30 x 45 cm polybags, where they can reach about 3 m (10 ft) in six months.
Plant out after 3-4 months in bags during the wet season (USDA), or at about six months (TNAU). Choose an open, sunny spot with room for a crown 12-18 m (40-60 ft) wide, at least 3 m (10 ft) from paving, walls and drains, and sheltered from strong wind.
Water regularly until the tree is established. Prune early to build a single strong trunk and keep main branches below half the trunk's thickness, as the wood is weak and breaks easily.
Cause: the hard seed coat was not broken. Fix: nick or sand each seed until the inner layer shows, soak 24 hours and resow.
Cause: cold, waterlogged mix. Fix: use a free-draining mix, keep it warm and water less.
Cause: shade or a young tree. Fix: grow in full sun; trees usually start flowering after 3-5 years.
Cause: weak wood and wide, low limbs. Fix: prune young trees to space out branches and remove narrow forks.
Cause: large surface roots. Fix: plant well away from structures from the start.
Royal poinciana is planted in frost-free regions throughout the tropics. Where frost occurs it can only be kept as a young plant in a heated greenhouse.
It tolerates sand, clay, loam, and acid or alkaline soils if drainage is good, and copes with dry spells once established.
The tree may drop its leaves in the dry season, and its dark pods, 30-60 cm (1-2 ft) long, hang on through winter before falling.
In South Florida UF/IFAS lists the tree as one to manage so that it does not escape into natural areas; check local advice before planting near wild land.
Nick the seed, sow it warm and raise your own flame tree.
The hard coat keeps water out. Nick or sand each seed, or treat it with hot water, then soak it for 24 hours. Untreated seed may lie dormant for a long time.
On a good site, in full sun, trees can flower in 3-5 years.
Only while it is young. It becomes a large spreading tree and is best planted out in a frost-free garden with plenty of space.