What You Need to Know About Growing and Caring for Hibiscus
Hibiscus trees are part of a large genus of flowering plants that includes over 200 varieties—some edible, some not—which include everything from tropical ones that thrive best in heat to hardy options that can withstand the cold. Hibiscus is a small-to-medium-sized plant that can be pruned to appear shrub-like or its stems can intertwine giving the appearance of a tree, says Nandita Godbole, botanist, landscape architect, and cookbook author of Seven Pots of Tea: An Ayurvedic Approach to Sips & Nosh (from $35, amazon.com). A well-maintained hibiscus tree can grow up to eight feet tall, she adds, and its dark green leaves are about four to six inches long, with a toothed edge and a slightly stringy sap (because they belong to the okra family). "A healthy hibiscus bears large and showy flowers, of a minimum of five petals and a central stalk containing both the male and female parts of the flower," says Godbole.
Where to Grow Hibiscus
If you live in the southwestern part of the country, Quita Jackson, gardener and educator at GreenDesert.org, says that you can grow hibiscus all year long. If located in cold temperatures, she encourages that the plants be potted and moved inside for the winter months. According to Godbole, as a plant native to the tropics, hibiscus is a perennial in zones eight and up, or where temperatures do not drop below 50 degrees at night. "It can do fine in a greenhouse setting but thrives outdoors. In all [USDA hardiness plant] zones numerically below eight, hibiscus is an annual and must be replaced every year."
How to Grow Hibiscus
Hibiscus does not produce viable seeds. Nurseries produce healthy plants from a "stock plant" by either grafting or air-layering, says Godbole. These plants are more reliable than trying to start from seed or propagate. Jackson says that as a hardy plant, depending on the USDA hardiness zone, hibiscus can be planted directly into the ground, or you can put it in a pot or a bed. Either way, make sure your hibiscus is placed in an area with full sun, says Jackson—while some varieties can thrive in full morning sun with afternoon shade, most prefer stronger light conditions. With that in mind, Godbole recommends choosing a planting location that gets six to eight hours of direct sunlight and enough air circulation. "If the area is too hot, or if the soil drains away too quickly, it will need more frequent watering," she says.
Hibiscus requires soil that drains well, says Jackson, as hibiscus does not do well sitting in a bunch of water. For fertilizer, she makes a worm cast tea, and fertilizes the plants every two weeks. Godbole says that there are many well-balanced (with equal amounts of nitrogen, phosphorus, and potassium) and specialized fertilizers on the market created specifically for hibiscus.
Tips to Consider Before Growing
It's important to give the shrub plenty of space when planting in the ground, Jackson recommends digging a hole one foot by two feet deep to provide the roots with space before filling it in with compost. She also says to ensure each plant has about four feet between them to provide enough room for the branches to grow.
But giving hibiscus trees enough room to grow isn't the only thing to consider when planting. According to Godbole, pests happen more often on a hibiscus if its roots are wet or if two plants are planted too close to each other or to a structure. "The most common problems include mealy bugs, which cover the plant in white cottony spots. It is also susceptible to aphids, scale, ants, and whiteflies." These can be controlled with appropriate pesticides by inviting beneficial insects like ladybugs to the garden and/or pruning to improve air circulation in the hibiscus.