In cool climates, enjoy popcorn cassia as an easy-to-grow annual in containers and in-ground plantings where it will begin blooming when the heat of midsummer sets in, then continue its flower show until the first frost. Amplify its bold yellow flowers by pairing it with orange and magenta dahlias, color-drenched snapdragons, or bright purple Verbena bonariensis.
Popcorn Cassia Care Must-Knows
Popcorn cassia is easy to grow as an annual or perennial. In tropical regions, it will form a multi-stem shrub. Staking is helpful in Zones 9-11 where popcorn cassia puts on new growth each year and is rarely damaged by freezing temperatures. Plant popcorn cassia in full sun and rich, moist, well-drained soil. Start it from seed or begin with a rooted cutting. Seeds will germinate more readily when soaked in water for 24 hours. Sow seeds shallowly indoors in February or March and wait until all danger of frost has passed before transferring outdoors. Provide plants with ample water and fertilize as needed if soil is poor. Plants grow quickly and unfurl many new leaves and flower stems in heat and humidity. Expect the plants to slow their growth significantly when temperatures fall below 80 degrees F. Popcorn cassia will tolerate a light frost. In cold regions, it can be overwintered indoors in a greenhouse or a bright window. Bring the plant inside when nighttime temperatures are in the high 30s.
Beware of Invasive Look-Alikes
A member of the Senna genus (Senna pendula var. glabrata) is an invasive plant in South Florida and should not be planted. Senna pendula var. glabrata has the potential to spread to wild areas, displacing native species. When purchasing popcorn cassia, make your purchase from a reputable nursery and carefully check the plant tag before buying to ensure you have Senna didymobotrya.
