Hibiscus is a beautiful, hardy, tolerant, and easy-to-grow shrub, fully hardy and a source of wonder when its branches are laden with large flowers. Hibiscus is a profusely flowering shrub, suitable for the somewhat smaller garden or patio planter, reaching around 1.2-1.5 metres in height if left un-pruned. Or plant in a row to form an unusual deciduous hedge.
Difference between a hardy and tropical hibiscus plant
The main difference between a hardy and tropical is where they are best situated to grow. A tropical (indoor) hibiscus prefers to grow in warmer climates and often requires being brought indoors during winter as frost can kill them. In contrast, hardy hibiscus can survive some of the colder winters.
Despite the main difference, we should note that a difference between the two is the bloom types, leaves, and care requirements. With that said, we have provided care instructions below for both types of hibiscuses.
The deciduous hibiscus plant blooms bushy flowers in summer and autumn in a mix of colours. They grow best in a mixture of soils (chalk, clay, loam, and sand) so long as the plant is in moist, well-drained soil. For the best outcome, grow in full sun to partial shade in a sheltered south or west-facing garden.
The growing conditions for hibiscus plants depend on factors such as the specific variety (hardy or tropical) and whether they are grown indoors or outdoors.
Hibiscus plants thrive in bright conditions, so it is best to provide them with partial to full sun. If your hibiscus is not blooming, consider moving it to a sunnier location. For indoor tropical hibiscus, place them near a sunny window but avoid exposing them to intense, direct sunlight. When transitioning your plants from indoors to outdoors in warmer weather, gradually acclimate them to brighter conditions.
To ensure optimal growth, hibiscus plants require well-drained, fertile, and moist loamy soil. Hardy varieties, which are native to wetlands, are suitable for locations that tend to be excessively wet for other plants. Most hibiscus plants prefer slightly acidic soil pH, although the ‘rose of Sharon’ variety can tolerate alkaline conditions. It’s worth noting that soil acidity levels can affect the colour of hibiscus flowers. Applying a layer of mulch around the base of the plants can help retain moisture, especially during dry conditions. If the soil lacks nutrients, amending it with organic matter will provide significant benefits.
Hibiscus plants have high water requirements and should be kept consistently moist. For indoor tropical hibiscus, water them regularly from spring to early autumn, which is their active growing season. During dormant periods, reduce watering significantly. When it comes to container-grown hibiscus, allow the top inch or so of the potting mix to dry out completely before watering again.
‘Rose of Sharon’ and hardy hibiscus varieties can tolerate cooler climates. If frost is a concern, it is advisable to bring container-grown plants indoors, placing them away from radiators and preferably in a conservatory.
Feed hibiscus plants with fertilisers high in potassium and nitrogen to promote abundant and vibrant blooms. Apply a half-strength solution just before the start of the bloom period and continue feeding every few weeks until the end of the flowering season. This will help ensure healthy growth and enhance the colour of the blooms.
How to grow hibiscus
To grow outdoors, you must ensure the soil is moist and well-drained in a sunny spot with shelter. These also grow well in pots with loam-based, peat-free compost.
If growing indoors, place the hibiscus in a bright spot away from direct sunlight. The minimum room temperature should be 7’c and high humidity. The ideal room would be a bright bathroom or kitchen.
Ongoing care for hibiscus plants
Use a slow-release high potash formula feed every spring. Mulch in autumn, but don’t be surprised when your hibiscus dies back after a hard frost (they are deciduous, so this is normal). Cut back stems to 10cm above ground level as they will regrow in the following spring but be aware that late development is normal for outdoor hibiscus. Give an annual prune after the hibiscus has been established for three years; this will keep the growth under control.
During spring to early autumn, give regular water and feed fortnightly with a high potash liquid feed. Over late autumn to early spring cut down on watering as the plant will be dormant. Allow for the top few centimetres to dry out between watering. Shorten the previous year’s growth in early spring to allow new growth to shoot.
Traditional tropical hibiscus can live up to 50 years but most newer hibiscus hybrids live up to 10 years.
Yes, hardy hibiscus plants will grow back in spring after going dormant in autumn and winter.
This is probably caused by inadequate growing conditions including sunlight, humidity and over or under-watering.