The royal poinciana tree--scientifically known as Delonix regia and also called the flame tree, the flamboyant, and the Mohur tree--features bright orange flowers, feathery green compound leaves, and gracefully spreading branches that provide a welcome canopy of dappled shade. This fast-growing tree, which is native to Madagascar, can reach 30 feet tall and thrives in warm climates where winter temperatures don't drop below -3.89 degrees Celsius. Seeds of the royal poinciana tree sprout with little difficulty when correctly pretreated. By following some basic guidelines for seed stratification and germination, you can grow a lush, tropical royal poinciana tree from a seed.
Harvest the long, straplike seed pods when they fall to the ground in the spring after the tree has flowered. Crack the pods open and remove the hard, shiny, inch-long seeds. In order for the seeds to germinate, the seed coat needs to be softened--a process called warm stratification. Trying to germinate at least half a dozen seeds increases the odds that one or more will sprout.
Pre-treat the seeds by placing them in a pot of boiling water, then removing the pot from the heat. Add cold water until the water temperature drops to 43 degrees C/110 degrees F; the water will feel hot but not scalding. Leave the seeds in the water overnight to accomplish warm stratification. Twenty-four hours later, the membranes covering the seeds will peel off by themselves.
Add several inches of fast-draining, sterile potting mix to a clean, new seed tray to a depth of 3 inches, and sow the royal poinciana seeds 1/2 inch deep and 3 inches apart, firming the mix around the seeds to ensure good contact. Spray with a mister to avoid disturbing the seeds and potting mix, and set the tray in a warm place in bright, indirect light. Keep the soil consistently moist.
Provide adequate air circulation for your seedlings. Use an overhead fan, set on low. If you don't have a ceiling fan, you can use a small household fan, but don't aim it directly at the seed tray. According to the Tree Seeds website, good air circulation wards off bacterial and fungal growth, and promotes thick, sturdy stems.
Watch for the seeds to germinate--usually in about two weeks. Transplant the seedlings to 4-inch clay flowerpots when they each have two sets of true leaves, and place them in a sunny windowsill. Take care not to scorch the seedlings; morning sun is a better choice than afternoon sunlight. Within a few weeks, your royal poinciana tree seedlings will be ready to be transplanted outside.
To avoid risk of burns and scalds, use caution when adding the seeds to boiling water and again when adding the cold water to the pot.