Cassia Popcorn Plant: Growing Guide and Fact Sheet
The cassia popcorn plant (Senna didymobotrya) was once in the genus Cassia, hence its common name. This flowering shrub is known as the popcorn plant, because rubbing its leaves is said to produce a smell reminiscent of buttered popcorn—though to some people, the smell is closer to that of a wet dog.
The popcorn plant is native to tropical regions in central and eastern Africa. It is hardy in U.S. Department of Agriculture plant hardiness zones 9 to 11. It is often grown as an annual in colder climates. You can also grow this plant in a container and overwinter it indoors.
Cassia Popcorn Plant Identification
The cassia popcorn plant is a shrub with a typical height between 6 and 10 feet, though it is capable of growing up to 20 feet tall. These are semideciduous plants, meaning they lose their leaves but only for a short time.
Cassia popcorn plants have pinnate compound leaves, meaning each leaf has a central stem surrounded by smaller leaflets on both sides. A single leaf may be up to 18 inches long and may have anywhere between 8 and 18 pairs of leaflets, each about 3 inches in length. The leaflets are bright green and leathery and have some pubescence, or hair, on them.
Cassia popcorn plants have pinnate compound leaves.
From spring to fall, cassia popcorn plants produce round, bright yellow flowers that may be 1/2 inch to 2 inches wide. Each flower has five petals. The flowers grow in racemes on terminal flower spikes that are about a foot long. The flower buds are encased in a dark bract.
As a tropical plant, the popcorn cassia plant is a heat-loving species that blooms most profusely in late summer.
Growing the Cassia Popcorn Plant
Cassia popcorn plants can be grown from seed. Soaking the seeds for a day before planting will help speed germination. You can sow popcorn plant seeds directly in the ground, though it is important to wait until the danger of frost has passed.
Alternatively, if you are growing this species as an annual, you may prefer to purchase rooted cuttings to expedite the process.
When choosing a location for your cassia popcorn plant, note that this species performs best in full sun. Well-draining soil is important for the cassia popcorn plant in order to prevent root rot.
Cassia popcorn plants can be propagated by seed or cuttings.
Cassia Popcorn Plant Care
The cassia popcorn plant is a legume, as are beans. These plants interact with bacteria in the soil in order to convert nitrogen from the air into a form that can be used by the plants. Still, these plants benefit from feeding with a 20-20-20 fertilizer during the growing season.
It is sometimes necessary to prune popcorn plants to prevent them from getting too large, though this can interfere with reblooming.
While the cassia popcorn plant can handle light frost, if you want to keep this plant as a perennial outside of its hardiness range, it is best to grow it in a container that you can move indoors next to a sunny window in the winter.
Since beginning her career as a professional journalist in 2007, Nathalie Alonso has covered a myriad of topics, including arts, culture and travel, for newspapers and magazines in New York City. She holds a B.A. in American Studies from Columbia University and lives in Queens with her two cats.