Senna Didymobotrya, aka the popcorn cassia plant, is a cool plant that you’ll want to consider adding to your collection. And popcorn plant care isn’t difficult indoors or outdoors! Learn all about it here.
Popcorn plant care
When I first came across the popcorn plant, I knew I had to tell you all about it. What first caught my eye were the fluffy yellow flowers. I actually thought the flowers were the reason the plant was called a popcorn plant because they look like buttered popcorn.
But it doesn’t get the name “popcorn plant” from its flowers. Instead, the scent their leaves give off when you rub them does! It smells remarkably like buttered popcorn.
While that might sound absolutely delightful if you’re a popcorn lover, some people have a different opinion. In fact, they think it smells like a wet dog. I don’t get that at all…so you’ll have to see what you think!
Popcorn plant background info
The full name for the popcorn plant—or popcorn cassia—is Senna Didymobotrya. (It was originally part of the cassia genus, and it has retained that name despite no longer actually being a cassia.)
It originated in Central and Eastern Africa. This region is home to a tropical climate with plenty of heat and moisture. These days the popcorn plant can be found as an ornamental plant all around the globe, and has been naturalized in the United States (in certain parts) and Mexico.
What does the popcorn plant look like?
The popcorn plant has bright green, feathery, pinnate compound leaves. This is a fancy way of saying that it has a row of leaflet pairs along an extension of the plant. My dad thinks the plant looks like a weed becuse of the leaves 🙂
This plant will bloom almost year-round. In nature they can grow up to 25 feet tall, which is huge! Thankfully they don’t get nearly as tall as houseplants, and if it’s the flowers you want, you’ll want to keep it short.
The flowers grow in clusters on short stalks called racemes. Each raceme will produce about 20 bright yellow flowers, and black flower spikes—quite a unique sight!
This plant is actually a legume, meaning it grows small fruit pods in addition to flowers. Each of the pods produces about a dozen bean-shaped seeds, which makes propagating a breeze. (Warning: these pods are not edible!)
I have seen the popcorn plant in nurseries, but I hadn’t brought one home yet due to space. My mom decided to take the plunge and get one, though—so I have a lot of exposure to the plant! She planted hers outside in the backyard.
How long does it take for a popcorn plant to bloom?
Popcorn plants can bloom at all sizes. They can push out blooms as houseplants, but they will bloom prolifically outdoors with plenty of sun and warmth.
The plant can bloom anytime between spring and fall, but blooms generally peak in late summer when it’s god-awful hot out. At least something likes the heat.
Is popcorn cassia a perennial?
Yes, in some climates. It isn’t a perennial where I live. (Perennial means that the plant lives year-round or comes back year after year.) Popcorn cassia is a perennial in USDA growing zones 10 and 11—and maybe even 9.
I live in zone 7, where we have all four seasons and it can get extremely cold in the winter. Therefore, popcorn cassia either needs to come inside for the winter or live in a pot as a houseplant.
If left outdoors or in the ground, it will die off as soon as temperatures begin to drop in the fall, and it won’t return in the spring (which is an annual). However, some annuals do re-seed themselves around here, and popcorn cassia might, too.
Popcorn plant care & lighting needs
So let’s get into care needs. The popcorn plant comes from the tropics, so it loves the sun. It’s pretty simple in that regard, just find a spot with plenty of direct sunlight, and you can count on it to bloom from spring to fall.
Don’t worry about burning the foliage on this plant. My mom has hers planted in a very sunny spot that gets direct light almost all day, and it has flourished.
Popcorn plants can be grown indoors by a very bright window. But this plant will not do well in even bright indirect or medium light levels for long. And if you’re one of the few that smells wet dog instead of fresh popcorn, outdoors is your best bet!
Popcorn cassia are legumes, so they need LOTS of water to stay healthy. If you’re growing the plant in an area where it is a perennial (more on that in a bit), watering is especially important in its first year. This is because the plant needs plenty of oxygen and nutrients.
If you’re growing it in a pot, water deeply twice a week. As an outdoor plant, keep an eye on how much it rains. It expects about an inch of rain every ten days, so if you live in a drier climate, be sure to supplement its water.
My mom has hers planted in the ground, and she basically planted it and let mother nature take care of the rest. If she’d opted to plant it in a pot, though, she would not have been able to take that much of a hands-off approach with our dry spells.
Try not to water in the evening because that’ll leave the roots to sit in water overnight and increase the risk of rot and fungal infections. However, it’s not a big deal if it rains in the evening or at night.
What kind of soil is best?
Like all tropical plants, the popcorn plant demands rich, moist, well-draining soil. Try combining a standard potting mix with a bit of compost. This will likely be a good balance of nutrients and drainage.
My mom simply added some compost and potting soil to the ground when she planted her popcorn plant. We have very dense clay-based soil here, so it often needs a bit of improvement to help plants grow.
If you have your plant indoors, you can use any standard well-draining indoor potting mix to ensure optimal popcorn plant care. Make sure the pot you’re planting it in has a drainage hole.
Temperature & humidity
These beauties come from the hot, humid regions of Africa—and I do mean hot. We’re talking consistently above 80 degrees Fahrenheit! This is another factor to consider if you’re thinking about getting your hands on a popcorn plant.
Every once in a while a cold day won’t harm it, and as it matures its tolerance will improve. But for the most part its growth is contingent on high temperatures. (See more on winterizing the popcorn plant below for more info.)
The popcorn cassia also needs high humidity levels, at a minimum 60%. This kind of humidity can be hard to imitate and maintain indoors. So if you live in a humid, hot region, the popcorn plant will absolutely thrive outdoors!
We have very hot, humid summer in Maryland, so it’s really the perfect climate for these plants—at least in May through September! It needs to come indoors once it starts getting cold.
Want more yellow in your garden? Check out my post all about caring for a Meyer lemon tree!
How do you overwinter popcorn cassia?
Now that we know the popcorn plant cannot tolerate cold weather and basically needs a sauna year-round, you might be wondering how to preserve it over the winter. It’ll take some leg work, that’s for sure.
For that reason, you may just choose to treat it as an annual that you plant in the ground or in a pot. If you do plant the popcorn plant in a pot, this makes it easiest to winterize.
Before the weather dips down below 40 degrees Fahrenheit, dig it out of your yard and pot it in a large container (if it isn’t already in a pot). Move it indoors in front of your sunniest window.
You may also choose to supplement the shorter, darker days with a grow light to get you to spring. Once winter is over, you can transplant your popcorn plant back outdoors. It might look like crap, but it will rebound.
If that isn’t possible, or you just don’t have room indoors, you can overwinter the plant. Overwintering just means putting the plant in a semi-dormant state, and the process is much like overwintering any other plant.
After you dig up the plant and pot it, move it to a cool place with some light. Then, you’ll have to trim the plant down to half its original height—scary, I know.
As long as the stems are pliable, they can always grow back. Stop watering the plant until all leaves have fallen off, marking its shift into semi-dormancy. For the duration of winter, only water once every 6 weeks or so.
To bring it out of semi-dormancy in the spring, start to introduce more water gradually. You’ll notice leaves sprouting, and that’s when you can reintroduce it to the outside world. Your popcorn plant will soon rebound.
How do you propagate popcorn cassia?
The popcorn plant does most of the propagation work for you! Propagating through stem cuttings can be done, but it’s much more involved. The easiest way to propagate this plant is by dividing a larger plant.
To do this, you just dig the plant up or take it out of its pot and pull a section off with some roots. Transplant that into a pot with fresh soil and give it plenty of water while is acclimates.
Can you save seeds from a popcorn plant?
However, propagation is also achieved by harvesting the plant’s seeds. After the plant flowers, it will produce highly visible green seed pods. But don’t pick them just yet!
Wait for the seed pods to get crispy and brown to ensure the seeds are mature enough to harvest. You can pick off the seed pods and save them for next year—or immediately replant if you’re in the right climate.
For the best results, collect and sow them in springtime. Soak the seeds in warm water for 24 hours to help the germinating process along. Then you can plant the seeds in fresh, moist soil. Expect to see growth within a few weeks.
Like saving seeds? Check out my post on How to Harvest Zinnia Seeds!
Are popcorn plants poisonous?
Yes, popcorn cassia plants are poisonous. The name “popcorn” can be kind of misleading…so remember, it only smells like popcorn. It’s best to keep this plant away from nibbling animals or kids.
Do hummingbirds like popcorn plants?
Yes! Along with being pretty pest- and deer-resistant outdoors, the popcorn cassia plant attracts hummingbirds, bees, and butterflies. So if you’re wondering what the plant is good for…there’s no shortage of answers.
The bright yellow flowers would also look amazing planted alongside other brightly colored insect-friendly flowers in a container garden. By following the popcorn plant care tips in this post, I’m confident that the plant will be an interesting and welcome addition to your garden!