Overwinter that popcorn plant
Question: I have a popcorn plant that my friend gave me. Is there any way to keep it over the winter? She bought it from the Amish. The name is Cassia didymobotrya.
Answer: Popcorn plants are among the trendiest “new” plants you can find at local garden centers. Sometimes called peanut butter cassia, this African plant is a beautiful and fun ornamental for the garden or containers.
Though in our cold climate most gardeners grow popcorn plants as annuals, in warm climates that don’t dip below freezing, the plant is a shrub that reaches up to 25 feet in height.
The leaves of popcorn plant are elongated and composed of many pairs of smaller leaves. The bright yellow flower spikes occur off and on all summer, covering the plant in color and emitting the scent of slightly burnt popcorn. When rubbed between your fingers, the foliage bears the same fragrance.
Because it’s a member of the legume family, the flowers are followed by flat, bean-like pods that are not edible. Like other legumes, popcorn plants are capable of converting the nitrogen in the air into a form of nitrogen that fuels plant growth, making them also useful as a cover crop in farm fields and vegetable gardens.
If you’d like to try to overwinter your popcorn plant, you have several options.
The first is to dig the plant out of the garden and pot it into a large container of fresh potting soil. If the plant is already growing in a pot, there’s no need to repot it; just relocate the container. The plant can be kept outdoors during the day as long as the temperature remains above 40 degrees F, but move the plant indoors at night if a frost is expected. Once the temperatures regularly plummet below the 40 degree threshold, cut the plant back to half of its present height and move it indoors. Put the plant in a room with bright, but not direct, sunlight that’s kept relatively cool.
Do not fertilize your popcorn plant during the winter months as that will encourage new growth, which is not what you want to occur. Instead, cut back on the watering and turn the pot a quarter turn every few days to keep it from bending toward the window. If you have a grow light, keep it on for 12-13 hours per day. Once spring arrives and the danger of frost has passed, your popcorn plant can go back outside.
The second option is to overwinter the plant in a semi-dormant state. To do this, pot it up and trim it back to half of its original height. Move the plant into a cool garage or basement with only a small window. Stop watering the plant all together and let it shift into a semi-dormancy. The leaves will all fall off, but don’t let this startle you. As long as the branches remain pliable, the plant is still alive. Water sparingly once every 6 to 8 weeks and do not fertilize.
As soon as the days begin to lengthen in mid- to late March, begin to water the plant a little more. When April arrives, it will start to leaf out. When this occurs, you can take the plant outdoors and put it in a shady area on warm days, being careful to bring it back inside at night or anytime the temperatures are cold. Within a few weeks, your popcorn plant will be full and lush again. And by summer, you’ll get to enjoy those colorful blooms once again.