Crossandra is a genus of approximately 50 species of flowering plants in the family Acanthaceae. They are from tropical Africa, India, and surrounding countries. Crossandra infundibuliformis is cultivated worldwide as a houseplant, and tropical garden plant, for its colored flowers and deep-green, glossy leaves. Also known as the firecracker flower, this species is considered by some horticulturists to be underutilized in the United States given its ease of growth and nearly constant flowering.
The firecracker flower has been bred in Europe to create a number of cultivars with a variety of colors, ranging from orange to red and yellow. The original flower color is salmon pink. The flowers have an unusual disk-shaped appearance, and sprout from 4 to 6 inch (10 to 15 cm) long spikes. The oval leaves vary from 2 to 5 inches (5 to 12.5 cm) long.
The size of this plant can vary, depending on the cultivar and whether it is grown as a perennial in a warm climate or as an indoor houseplant. When grown as a permanent part of the garden, Crossandra forms bushes that generally do not exceed 3 feet (0.9 m) tall. They grow equally wide. As container plants, the firecracker flower usually does not exceed 1 foot (0.3 m) in height.
The light requirements of this species of Crossandra vary greatly depending on where the plant is grown. In the southeastern United States, such as in Florida and Mississippi, for example, full to partial shade is recommended. It is suggested to grow the firecracker plant with ferns, impatiens, and hostas in these areas. This plant is sometimes grown as a low maintenance short hedge in Florida. In contrast, full sun is recommended for plants in Malaysia and California.
Firecracker flowers prefer to be grown in moist, well-drained soil that has been supplemented with organic matter. Both garden and container plants should be fertilized regularly. It is recommended to plant Crossandra seeds in late spring in central Florida, where these types of plants are often grown as annuals. The plants do not tolerate cold well, as their leaves turn black at 55°F (12.8°C). Colder temperatures will kill them.
The plants should have the dead flowers pinched off. They should also be continually pruned back, to keep them bushy and flowering. Plants in warm climates, that are grown under desirable conditions, will bloom all year. This is also true for houseplants, which are recommended to be grown in soil with a pH of 4.5 to 5.5. In the house, the plants should receive humidity and bright sun, except during the hottest times of the year.
In the tropics, it is popular to string the small flowers together. They are often used by women to decorate their hair. Also, they are frequently combined with jasmine, and given as offerings at religious temples. Crossandra has an additional benefit of attracting butterflies.