I have complied all the sources of information I could find on culture, care and propagation of the Bird of Paradise plant.
The plant itself can reach up to 5 feet in height with a 2-3 foot spread. The plant is trunk less, compact and clustering but slow growing with fleshy roots. S. reginae has banana shaped stiff- leathery, concave, oblong, bluish-gray leaves with a pale or red midrib. The leaves are attached to a long stalk that sometimes reaches up to 2 feet in length.
Because of the banana shaped leaves and other plant characteristics it was classified in the banana family Musaceae, however now it has its own family Strelitziacea. The name Bird of Paradise comes from the spectacular flower shape which resembles a birds beak and head plumage.
The Bird of Paradise flower is a spectacular blossom. Long stemmed flowers emerge from green boat-shaped bracts which are bordered in red or purple. The numerous pointed petals of brilliant orange are contrasted with an arrow-shaped tongue of vivid blue. Some species have white and blue.
The flowers have several "sets" of flowers in each bract which are formed on the end of a stalk. Beginning normally in the winter and spring the flowers will come out in succession over a period of time. In colder climates greenhouse grown plants can bloom intermittently all year round. According to Graf by keeping the plant cool and dry in the spring flowering can be delayed until summer.
If started from seed it takes five to seven years for blossoming to begin. Some text suggest three years from seed.
Even as cut flowers the succession of bloom will continue to occur and last for weeks if the water is changed regularly. (While no one has defined regularly most likely once a week is sufficient.)
The flowers have no scent.
The Strelitzia reginae prefers full sun, 4000-8000 ft-candles, but can tolerate 2000 ft-candles. However flowering will be diminished at 2000 ft-candles. It is a warm temperate plant preferring 65-70 degrees F during the day and 50-55 degrees F at night. They prefer moderate humidity, around 60%. This may require some daily misting during the dry winter months. In areas of the world where there is no danger of frost it can be planted outdoors. Elsewhere it will need to be brought indoors in the fall when temperatures begin to drop in the 50's (F). Overwintering should be done in a cool place where the temperature will be 50-55 degrees F. An alternative for outdoor culture in climates that have frost is to permanently plant a slightly bigger pot in the ground and place your potted Strelitzia in this pot and cover with a mulch. It looks like an in ground plant, but when cool weather comes and it is time to bring it in you just lift it out of the ground and bring it inside.
The plants should be watered and fertilized according to growing conditions. Most often the Strelitzia is underfertilized. When you do water thoroughly wet the entire potting mix and allow to it dry out slightly before the next watering. Use discernment in the amount of fertilization you use. Overfertilization will lead to excessive foliage and little or no flowering. Here are general guidelines by season.
Start to water more regularly and feed the plant every other week.
The plant can be grown outdoors when the temperatures reach around 60-70 F. Water regularly and fertilize each week.
Watering should decrease as the light intensity decreases.
Water sparing during the winter until blooming begins, then gradually increase the frequency of watering.
Overwatering, especially in the winter will lead to root rot, which will spread upward into the crown ( just above the soil surface). If noticed in time stop watering for a while. If the problem continues to spread up the stems then a fungicide should be used. See pest below for more details.
Strelitzia reginae are relatively pest free. For practical purposes they have no problems, but occasionally some pest problems occur.
Caused by overwatering, a combination fungicide of ethazole + thiophanate-methyl gives very broad coverage of the root rot causing organism. This fungicide can be found under the trade name of Banrot. Thoroughly soak the soil as well as the crown with the fungicide mix.
Scale insects can be treated with insecticidal soap or removed by hand with a sponge and soapy water. It is recommended that you take a damp sponge and clean the leaves once a month.
Nematodes cause a problem for the roots of Strelitzia. Use clean potting mix or soil when repotting, topdressing or any other type of soil changing. Keep pots off of the ground to prevent nematodes from infecting the potting media from your native soil.
The Bird of Paradise can be propagated by either seeds or division of the crowns. Seeds take considerably longer than division to grow into a blooming plant.
The Bird of Paradise seeds have a very hard seed coat. Before planting them you must scarify (break the seed coat). Take a file and scrape the outside of the seeds just enough to break the seed coat. Sow seeds in a propagating mix or make your own mix by using equal parts of sand and potting soil. Seeds must be fresh, less than 6 months old and absolutely less than a year old. Germination occurs best at 75-80 degrees F. Germination is a slow process for Strelitzia seeds. Anywhere from 2-3 months.
Once your seedlings have emerged and have three to four leaves move them into a well drained potting mix. As the plants grow keep moving them to larger pots.
Remember though that they bloom better when crowded, so be slow to repot and quick to leave alone. One of the best specimens of Strelitzia reginae I have ever seen is one at a garden center that is about 15 years old and hasn't been repotted for at least 10 years. The container has burst from the pressure of the numerous crowns, but it always has three to four flowering stalks on it year round!
When the plants have grown strong divide them to make more plants. Dividing in the Spring is preferred, however you can divide mostly year round.
Outside of that just topdress the pot with a clean potting mix when the soil level starts to get to low. Only repot when it is absolutely necessary.
If you desire to use the blooms in floral decorations which needs a preserved flower the Bird of Paradise will fit into your plans. Take a flowering stalk from the plant and some leaf stalks if you wish. Crush the cut end of the stalk and place it in 4 or 5 inches of a water solution containing 1 part glycerine and 2 parts water. After the glycerine has penetrated the entire surface area of the stalk, the stem/leaf color will change and begin to ooze at the edge. This should take a week or so. When the stalk is saturated remove and hang upside down until thoroughly dry. Obviously this can get messy so you need a place to allow dripping of the solution onto a floor or table.
Author F. Brian Smith 3/97