Popcorn Plant Facts
Kids love to garden, and if you grow the popcorn cassia (Senna didymobotrya), yours will love it even more. The shrub’s foliage smells like popcorn and the fragrance of the cheerful yellow flowers is like peanut butter. These are all attractive attributes for kids, so warn them that the plant isn’t edible. All parts of the cassia popcorn are poisonous and eating them may be fatal.
Popcorn Plant Basics
Popcorn cassia is a tropical plant, which is evident in its feathery, ferny foliage. The shrub’s buttery yellow flowers spring from black buds in spring through late summer. Arrayed along a tall flower spike, the flowers on the bottom open first. Popcorn cassia is can grow 25 feet tall but typically tops out at 6 to 10 feet.
Where to Plant
A perennial plant, popcorn cassia grows in U.S. Department of Agriculture plant hardiness zones 9 through 11. If you live in a lower USDA zone, you can treat it as an annual. It requires a spot in full sun with consistently moist, well-drained soil. It bears seeds prolifically and the seeds travel and infest waterways, woodlands and grasslands. For this reason, it is considered invasive. Do not plant it if it's considered invasive where you live.
Popcorn Plant Care
While the cassia popcorn will tolerate drought conditions it is more attractive when you water it regularly. Never allow the soil to dry out completely. Fertilize the shrub in spring when you see new growth with a fertilizer that is low in nitrogen and high in phosphorous, such as 3-12-6 blend. Mix 1 teaspoon of the fertilizer in 1 gallon of water, or follow the instructions on the label, and pour the solution on the soil around the plant. Popcorn cassia doesn’t need pruning and isn’t bothered by insect pests or wildlife.
Growing From Seed
Planting from seed takes a long time and is only practical within popcorn cassia's USDA hardiness zones. If you live in a cooler climate, your best bet is to purchase a seedling from a nursery or an online retailer. To grow from seed, soak the seed in water for 24 hours to soften the seed coat. Sow the seeds in spring, after the last frost date in your area, when air temperatures remain above 61 degrees Fahrenheit. Plant the seeds 2 feet apart on the surface of the soil and sprinkle a 1/8-inch layer of soil over them. Water often enough to keep the soil slightly moist.
Based in the American Southwest, Bridget Kelly has been writing about gardening and real estate since 2005. Her articles have appeared at Trulia.com, SFGate.com, GardenGuides.com, RE/MAX.com, MarketLeader.com, RealEstate.com, USAToday.com and in "Chicago Agent" magazine, to name a few. She holds a Bachelor of Arts in English with a concentration in creative writing.