Tropical hibiscus varieties (Hibiscus rosa-sinensis) are perfect if you live in a warm climate or want an impressive houseplant. For those living in cooler parts of North America, opting for a hardy variety or the shrubby rose of Sharon (Hibiscus syriacus), which are both easier to grow and can withstand colder winter temperatures, will be the better choice. Regardless of variety, hibiscus flowers are very attractive to butterflies and hummingbirds. While all hibiscus have similarities that go beyond appearance, they have some distinct care and growing requirements.
Light
Hibiscus love bright conditions. In northern climes, full sun is often best, but in the intense, dry heat of the south, filtered sunlight is better. If you find that your plant isn’t producing many blooms, move the plant to a sunnier location. Indoor tropical hibiscus will need a bright spot near a sunny window but keep it away from strong, direct sunlight. If you are transferring your plants outdoors when the warmer weather arrives, gradually acclimate them to the brighter conditions.
Soil
All hibiscus do best in well-drained, fertile, moist, loamy soil. The hardy varieties are wetland natives and are a good choice for sites that are too wet for other plants. Most hibiscus prefer a slightly acidic soil pH, but the rose of Sharon is tolerant of alkaline conditions. The color of hibiscus flowers can be affected by the soil acidity level. Mulching around the plant base can help with moisture retention if your location is experiencing dry conditions. For nutrient-poor soil, amending with organic matter will be beneficial.
Water
All hibiscus are thirsty plants that need to be kept moist. Indoor tropical hibiscus benefit from regular watering from spring to early autumn during the growing season. Significantly reduce watering during dormant periods. For container-grown plants, ensure the top inch or so of potting mix dries out fully before watering—saturated soil is also problematic, and make sure containers have adequate drainage holes. Depending on the conditions, you might need to water your hibiscus daily to help it produce an abundance of blooms. If your hardy hibiscus are not planted near a pond or in another wet area, water them on a regular basis to keep them moist.
Temperature and Humidity
Rose of Sharon and hardy hibiscus can grow in cool, temperate climates. They thrive in temperatures from 60 to 90 degrees Fahrenheit but can handle temperatures as low as 20 degrees Fahrenheit. When temperatures drop below 30 degrees Fahrenheit and frost is a risk, bring container-grown plants indoors. However, be mindful of their higher humidity requirements—which is why bathrooms are a good location for these plants. Temperatures below 50 degrees Fahrenheit can kill tropical varieties, so they are best housed in humid locations indoors in regions where this is likely to occur.
Fertilizer
To encourage abundant, healthy blooms with good color, feed plants with a high potassium and high nitrogen fertilizer. Fish emulsion and seaweed extract are organic fertilizers. Feed a half-strength solution just before the start of the bloom period and continue at least once every few weeks until the end of flowering.
Types of Hibiscus
There are hundreds of tropical and hardy hibiscus hybrids and cultivars available. Just a few popular varieties include:
Swamp Hibiscus (Hibiscus coccineus): An unusual, hardy species featuring large pinwheel-like flowers Confederate Rose (Hibiscus mutabilis): This hardy rose mallow has large, showy flowers that open white and then change color. Hibiscus rosa-sinensis ‘Cajun Cocktail’: A tropical cultivar with striking orange and yellow ruffled blooms, giving each one a one-of-a-kind appearance. Hibiscus moscheutos ‘Perfect Storm’: A hardy, compact hybrid cultivar that blooms late in the season.
Pruning
Hardy hibiscus benefit from annual winter pruning once they are established. Cutting the plant back after flowering, especially dead, damaged, and diseased branches and old wood growing in the center of the plant can aid air circulation and keep the plant looking tidy. Don’t worry if you cut back aggressively; this species can handle it.
Propagating Hibiscus
Most hibiscus propagation is from cuttings. Select a four- to six-inch piece stem from new, vigorous growth. Keep the leaves at the top of the stem but remove all the rest. You might want to dip the cut end in rooting hormone before potting in a well-drained, moist potting soil. It can take a couple of months for the root system to fully develop.
How to Grow Hibiscus From Seed
Growing hibiscus from seeds is more challenging than propagating from cuttings. They often take a long time to germinate and need a fair bit of attention. Nicking the hard seed coating slightly and soaking the seeds for up to eight hours can speed up the germination process as it allows more moisture to penetrate the seed. For best results, place the seeds in a warm, sunny location (at least 75 degrees Fahrenheit) and sow seeds about a quarter-inch deep. After a few weeks, seedlings should appear. With their fragile stems, they will need careful translating and gradual hardening off.
Potting and Repotting Hibiscus
Nutrient-loving potted hibiscus will benefit from being repotted every couple of years in early spring. Avoid deep pots, otherwise the plant will spend a lot of its energy on root development, and you want it to focus on flower production.
Common Pests
Hibiscus are not bothered by many pests or diseases, but red spider mites can be problematic when humidity levels are not high enough. Aphids are sometimes an issue too, but they can be kept at bay with regular cleaning or insecticidal soaps.
How to Get Hibiscus to Bloom
The exotic flowers on a hibiscus are short-lived, lasting from just one to three days. But if you have a healthy plant, they should produce many flowers through their growing season from late spring through fall. To prevent flower drop, make sure the plant is not being exposed to temperatures that are too hot or too cold. Frost is a problem, even for hardy varieties, and prolonged temperatures above 85 degrees Fahrenheit will cause flowering problems even for tropical hibiscus. Deadheading isn’t necessary, but bloom production can be impacted if your plant is overly dry or is not receiving enough nutrients or sunlight.
Common Problems With Hibiscus
Hibiscus are rather particular about conditions, and if you can’t meet their requirements, there are some common problems to watch out for.
Yellow Foliage
If you see your plant’s leaves turning yellow, it could be that you are subjecting it to sudden changes in weather conditions, not watering correctly, or not fertilizing often enough. Expect a little yellowing during the transitional seasons of spring and fall, but anything extreme merits further investigation.
Dropping of Buds
Extremes in temperature, not enough light or humidity, and over or under watering can cause bud drop.
