I often receive e-mails with questions about growing frangipani trees, and some readers may like to try growing them from seed. Paula Pugh Schipp of the Frangipani Society of Australia says that frangipani trees grown from seed grow much faster than those grown from cuttings because the root system starts to form when the seed germinates. Another advantage of propagating these lovely (Plumeria) trees from seed is that trees grown from cuttings will always be the same as the parent tree, but trees grown from seed are, like children, not usually exact duplicates of their parents. You may grow a tree with flowers with an entirely different colour combination if you have a variety of frangipani trees in your area.
Frangipani flowers do not always produce seed as the self-pollinating flowers do not always release their pollen. You can try hand-pollinating flowers with a piece of thick fishing line. Place the end of the line deep into the flower and wriggle it very gently to release the pollen. You have to be gentle as it is easy to knock the flower from its stem.
Seeds develop within a pod, often a double pod in a ‘T ‘ shape, which looks rather like two thin 17 cm zucchini in the early stages – changing over time to brown/black when mature (see photo, lower left). Pods can take up to 8 months to mature depending on the local microclimate.
When the seeds are mature, the pods become brittle and begin to split open revealing up to 60 seeds in each pod. Collecting the seed takes a bit of good timing because each of the seeds has a small ‘wing’ attached and, when the pod completely opens, the seeds can be spread far and wide on the breeze (see photo, below right). If the pod is in a position where you can easily observe its development, when the pod is just beginning to split, place a large basin under the pod structure and carefully cut the adjoining stem from the tree. If the pod is high in the tree and hidden by foliage, then when the pod starts to change colour, make a bag from nylon netting large enough to hold the pod structure with some room to spare. The will prevent the seeds from blowing away when the pod opens.
If you would like to try growing frangipani from seed, for best results sow them soon after they are collected.
This excellent Frangipani website provides a detailed guide to propagating frangipani, including an interesting method of germinating seed in paper towels: Frangipani Society of Australia