Root division is the simplest way to propagate a giant bird of paradise, but keeping in mind that the plant can grow to 30 feet tall, that may not be saying much. Propagation by division will produce flowers in two to three years, while propagation will take considerably longer, up to 10 years. The flowers are worth waiting for. The giant bird of paradise produces white flowers 18 inches long with a blue tongue and reddish-brown bracts.
The giant bird of paradise has a fleshy root system called rhizomes. In order to divide the roots, you’ll have to get at them first. Carefully dig with a shovel to unearth part of the root system. You could also remove any young offshoots that appear instead of digging and severing a section of rhizome. Take a sharp, clean knife and cut off a section of the rhizome that has at least four to five young shoots. Divide roots in late spring or early summer.
Fill a small pot -- 3 to 6 inches -- with a well-draining potting soil that has little to no peat moss, but a little organic matter. Plant the rhizome section and water it well until the soil is sufficiently moist. Place the pot in indirect sunlight for eight weeks, as Clemson University recommends, then move the pot to bright light as its leaves develop.
The new plant should put out its own roots in about three months, according to The University of Hawaii at Manoa. Plant it outside at the same depth as the parent plant and keep the soil moist.
Propagation By Seed
Propagation by seed is another option. Flowers that are allowed to go to seed will produce 60 to 80 seeds in a single pod. The seeds are black with orange tufts, suitably flashy for such a plant. Plant the seeds before the seed coat hardens in a loose soil with organic material and place it in bright, indirect light. Keep the soil moist. The seeds will germinate in two to three months. They are safe to transplant into a larger pot when they have two or three true leaves, according to the University of Hawaii.