Royal poinciana (Delonix regia) is beautiful tropical tree in the legume family. Like many other plants in the family, it develops a seed pod containing several seeds with a hard seed coat that can prevent the seed from absorbing moisture to germinate. To get around this hard seed coat, do one of the following:
1. Dip the seeds in boiling water for 4 minutes, then soak in room temperature water overnight.
2. Make a nick in the seed coat with a file or sharp knife opposite the embryo end. You'll be able to see a small scar on the seed coat at the embryo end where the seed was attached to the pod. Soak overnight as with method number one.
Sow the treated seeds in moist potting mix in a deep container at room temperature or slightly warmer.