How to grow hibiscus
Tips for outdoor and indoor care of this showy plant
While standard hibiscus plants prefer full sun, these hybrids will take a little shade–filtered light with at least one hour of direct sun is optimal.
Water plants generously while the weather is warm and the plant is growing. In winter, water more sparingly. “It’s better to let the soil get a little dry than to overwater,” Black says.
All hibiscus need excellent drainage, and these hybrids are no exception. Add organic amendments to heavy clay soils before planting or plant in raised beds. When using pots, mix some pumice or sand into your potting soil.
Feed actively growing plants frequently. Ideally, apply a little diluted low-phosphorous fertilizer (such as 20-10-20) with every watering. If you find that regime difficult to maintain, try adding controlled-release granular fertilizer to the soil at planting time; if the foliage begins to lose its lush, dark green look, begin feeding with liquid fertilizer.
Aphids, spider mites, and whiteflies are the most likely pests. A blast of water will dislodge them: Attach a water wand or spray nozzle to a hose and spray the plant thoroughly, being sure to wet the undersides of leaves. For heavy infestations, use horticultural oil or insecticidal soap mixed with water, following instructions on the package. In areas where it is present, giant whitefly can also be a problem, though these plants don’t seem to be as attractive a host as regular hibiscus.
Hibiscus thrive at room temperatures in the 60° to 70° range or higher. Plants bloom best when they receive one or two hours of direct sunlight per day. Good locations are south- or west-facing windows or under a skylight away from cold drafts. If you can’t provide these, use grow lights. Water once or twice weekly, as needed. Feed twice a month with a low-phosphorous fertilizer, as recommended above.
The main pest problem indoors is spider mites. Place the plants in the shower and rinse the insects off with a strong spray of lukewarm water.