Hibiscus is an attractive plant which produces distinctive trumpet-shaped flowers. While tropical varieties are best grown undercover, hardy varieties can thrive in a garden. Their flowers, in shades including red, pink, peach, orange, coral and white, attract hummingbirds and butterflies to your garden.
This guide will help you to add the hibiscus to your garden.
The distinctive flowers of the hibiscus make this a popular garden plant. Despite its showy appearance, these plants are pleasingly easy to grow.
While there are dozens of different species of this showy plant there are two main varieties. The first is the hardy outdoor type, usually classified as Hibiscus syriacus. This will grow in USDA zones 4 and higher.
The other type of hibiscus is tropical. Usually grown as an indoor evergreen, these will survive outside in USDA zones 9 and warmer. These are normally named Hibiscus rosa-sinensis.
Indoor varieties will flower from May until October. However they can be more difficult to care for and to get to flower every year.
These attractive plants come in a range of vibrant colors. Their colorful blooms, and rich green foliage, will add color to containers, borders or window sills throughout the flowering season.
Varieties growing outside are easier to care for. As long as they receive plenty of light they will reliably flower every year.
Popular hardy varieties include Blue River II, which produces attractive white flowers, the pink flowering Sweet Caroline and Lord Baltimore, a red flowering variety. Kopper King, named for its copper colored foliage it produces large pink flowers with striking red centres.
Where to Site Your Hibiscus
Hibiscus plants thrive in full sun positions. Ideally they need 6 to 8 hours of direct sunlight every day.
Hibiscus flowers are delicate and can easily tear or damage in the wind. For this reason the plants will also need shelter from the wind.
Hibiscus plants are a great choice for container gardens.
Tropical varieties, which like the temperature to remain over 45℉ are particularly suited to container gardening. This is because you will be able to relocate the plants indoors in the fall.
These are sun loving flowers, their blooms will turn and twist as they grow towards the light. Placing them in a full sun position will result in happy plants, with a healthy growth habit.
How to Plant Hibiscus
Hibiscus plants are commonly purchased from nurseries or garden centers as young plants. They can also be started from seed. Sow seeds in a modular cell tray filled with damp seed or general purpose compost 12 weeks before the last local frost date.
Before sowing, soak the seeds in warm water for at least an hour. This will soften their hard shells, helping to encourage germination.
After sowing, cover the seeds with a thick layer of soil. Place the cover on the tray, or place in a plastic bag. Place the tray in a light position. Regularly check the soil to make sure that it doesn’t dry out. Following germination remove the plastic cover and allow the seeds to grow on.
Once the last frost date has passed, harden the young plants off before transplanting into their final position.
Before planting you will need to prepare the soil. These plants like rich soil. Before planting work in plenty of compost or earthworm castings. Ideally the soil will also be slightly acidic, a pH between 6.5 and 6.8.
If you are planting in a container, you will need to fill the container with well draining potting soil. Mixtures designed for acidic plants are ideal. The container should be clean and have drainage holes in the bottom.
Prepare the soil properly before planting. This may be time consuming but is well worth the effort. A well worked, enriched soil will help your plants to establish themselves quickly.
How to Plant
Dig a hole in the soil deep enough to hold the root ball. The hole should also be at least twice as wide as the root ball.
Carefully remove the plant from its container and position in the hole. Backfill the hole halfway, being careful not to overly compact the soil. Water in well. As the water drains it settles the soil, eliminating air pockets.
Fill the hole and gently firm down the soil. Apply a layer of mulch or earthworm castings around the base of the plant. Water in well, making sure the soil and castings are moist.
If you are planting more than one, space each plant to a distance of 3-6 ft.
Hibiscus can also be planted in containers, either as part of a container garden or to grow as a houseplant during the cooler months. Your chosen container should be large enough to hold the fully grown plant. It should also be clean and have drainage holes in the bottom.
Fill the container with fresh, general purpose soil. Make a hole in the soil large enough to comfortably hold the root ball and plant as above.
Position hibiscus plants in a light position. Avoid planting in direct light. The temperature should be consistently between 45 and 50 ℉. The plants also prefer a humid atmosphere.
Plant as you would in the ground. You will need to re-pot every few years to prevent plants from becoming pot bound and stunted. The best time to plant is in early spring, between March and April.
Indoor plants can be placed outside during the summer. Again, make sure that they are protected from direct sunlight. As the temperatures begin to fall, at the end of summer, remember to bring the plants back inside.
Your plant will thrive if placed in a light, but not overly bright, warm position. Remember to water and tend to your plant regularly. During the warmest weather the plant can be placed outside, but remember to return it to its regular position when temperatures begin to fall.
Caring for Hibiscus Plants
Hardy varieties, despite their showy appearance, are easy to grow as long as they are in full sun and the soil is well draining.
Remember, also, to regularly weed around the plants. Weeds can quickly emerge, smothering small or young plants. They also take valuable nutrients and moisture away from more established plants.
Water and Fertilizer
Water plants regularly, aim to keep the soil evenly moist. Don’t allow the soil to dry out. In the week after planting you will need to water every day. This will help the plant to establish itself. Slowly reduce this to watering twice a week.
Harvesting rainwater will enable you to cut your water usage. Simply re-use harvested rainwater on your garden plants and crops.
When watering try to avoid getting the foliage wet. Damp leaves are a breeding ground for diseases such as mildew.
Applying an organic mulch, such as homemade compost, will help to keep the root system cool and the soil to retain moisture.
If growing in rich soil you will not need to fertilize plants. However you can apply a general purpose fertilizer in the spring to encourage new growth and flower production. Keep applying this every two weeks.
Liquid fertilizers are easy to use and can be incorporated into your watering routine. A high potash feed, such as rose food, can also be applied. If you want to know exactly what you are feeding your plants there are a range of plant feed recipes that you can make at home available.
Applying an Epsom Salt solution once a month will also help the foliage to maintain its dark green color.
Removing spent blooms will help to keep plants tidy. This will also promote new flower production. Dead or damaged branches should also be removed. This helps to keep plants healthy and disease free.
If the hard fall frost causes your plants to die back, prune them down to a height of about 5 inches. The plants will regrow in the spring. Some varieties may not begin to re-grow until May or June, so don’t be disheartened if new growth is slow to appear.
As blooms become spent they should be removed. Deadheading will help to prevent disease from developing on your plant. It will also encourage more blooms to emerge.
Companion planting is the process of planting mutually beneficial plants together. This helps to reduce infestations and disease while promoting healthy growth and flower or fruit production.
Hibiscus plants thrive in butterfly and pollinator gardens. They also make good companion plants. Coreopsis, baptisia, campanula and coneflowers all great companion plants.
Easy to grow plants such as alliums, iris, daylilies, poppies, delphinium and peonies are also all ideal companions. These enjoy similar soil and growing conditions to the hibiscus.
How to Propagate
Hardy varieties of hibiscus can be easily propagated. You can use the same technique to propagate tropical varieties, but this may take a little more practice.
Propagation From Cuttings
This is the prefered method of propagation. Cuttings will grow into exact copies of the original plant.
Take a 4-6 inch long cutting. The cutting should be taken from new growth or softwood.
Remove the foliage from the cutting, leaving just the top pair of leaves. The cutting can also be trimmed to just beneath the bottom leaf node.
While rooting hormone is useful in encouraging propagation it is not strictly necessary. Dip the cutting in rooting hormone if you are using it.
Fill a small, clean container with fresh compost. Alternatively an even mix of perlite and potting soil will also work. Dampen the soil.
Place the cutting in the soil. Gently firm the soil around the cutting. Place the cutting in a plastic bag, ensuring that the plastic doesn’t touch the cutting.
Place the cutting in a partial shade location. Keep the soil damp until the cutting has rooted, this will take about 8 weeks. To check that roots have formed gently pull the cutting. If it resists your attempt to dislodge it from the soil it means that roots are in place.
Once roots have formed, repot into a larger container and grow the cuttings on.
Hibiscus propagated from seed won’t grow true to the parent plant. For this reason this method is less common.
As the bloom becomes spent seeds will emerge. Collect ripe seeds and carefully nick them. This is best done with a sharp knife, Nicking seeds enables moisture to enter the hard shell, encouraging germination. Alternatively gently sand the seeds with fine grain sandpaper. Soak the seeds in warm water overnight. Again this will soften the shells, helping to encourage germination.
Fill containers or trays with fresh compost. Sow the seeds to a depth roughly twice as deep as the size of the seed. Water the soil and place in a light, but not direct sun, position.
Seeds will appear, if germination is successful, in two to four weeks.
Common Pests and Problems
Minor infestations, or those caught early enough, can be washed away with a blast of water from a hose pipe. For more persistent infestations a chemical or organic control should be applied. Alternatively you can make your own insecticidal soap.
Leaf diseases are also common. In particular powdery mildew and botrytis can afflict the foliage of your plants. Fungicide treatments should be applied as soon as you notice the problem.
Bud drop is a sign of an unhappy plant. This may mean that the plant is unhappy with its location, or is suffering from a lack or water or nutrients.
Bright and attractive, these plants are a popular addition to the garden or a houseplant collection. They are also pleasingly easy to care for.
Easy to grow, Hibiscus plants produce colorful attractive flowers. These will add interest, as well as attracting butterflies and hummingbirds, to your gardens. Meanwhile gardeners in cooler climates will enjoy growing these colorful plants in containers as houseplant during the winter months, moving them outside during the summer to enjoy the summer sunshine.