Tropical Hibiscus

When to Plant Tropical Hibiscus?

• The best time to plant Tropical Hibiscus in the garden is in the spring, at the start of the growing season.
• In mild climates (zone 11 and above), it may be possible to plant from late winter through fall.

Where to Plant Tropical Hibiscus?

Tropical Hibiscus have four basic requirements to grow healthy and bloom well: sun and warmth, excellent drainage, ample moisture, and nutrients.

Temperatures

• Tropical Hibiscus perform well in USDA Zones 10-12. They do not tolerate cold temperatures. A short cold snap as low as 37°F (3°C) is the limit for these plants. Not sure about your growing zone? Check here.
• Ideally, Tropical Hibiscus should be located where the temperature remains between 60-95°F (15-35°C) most of the time.
• If temperatures routinely drop below 50°F (10°C), growth and flowering will halt until it warms up again. However, the blooms will not be as large.
• Temperatures under 30°F (-1°C) for several hours will likely kill your Hibiscus.
• Temperatures over 95°F (35°C) often cause most flower buds to drop off.
• Tropical Hibiscus can survive temperatures as high as 115°F (46°C), as long as they have a steady water supply.
• Indoors: They can be grown indoors in a warm, sunny location where daytime temperatures are 65-75°F (18-24°C) and no lower than 55°F (13°C). Flower buds may drop off or fail to form if it is too cold.
• Select a site that is sheltered from cold drafts.

Light

• Tropical Hibiscus are easily grown in full sun in northern climates, but they will prefer partial shade in hot and dry climates. In too much shade, your Tropical Hibiscus may become tall and leggy, with a lower bud count and reduced flowering performance.
• Indoors: Hibiscus require very bright light to bloom well. A sunny western or southern exposure that has at least 4-5 hours of bright, direct light is best.

Soil and Drainage

• Drainage is critical. Tropical Hibiscus prefer neutral to slightly acidic, well-drained soils. Sandy loam soil is ideal.
• In sandy soils, use liberal amounts of thoroughly decomposed organic matter to adjust the aeration, drainage, and water-holding characteristics of the soil.
• In heavy clay soils, consider the use of raised beds to avoid periods of excessive moisture.
• If you are growing your Tropical Hibiscus in a container, use a rich, friable, loose, well-drained potting mix. 80% potting mix and 20% sand is quite standard.

Moisture

• Tropical Hibiscus are water-loving plants. They require regular water most of the growing season. Water should be directed to the root system, and the foliage should be kept as dry as possible. This practice will help limit foliar disease.
• During the winter months, allow the soil to dry out a little between watering.
• Tropical Hibiscus add an exotic touch to foundation plantings and shrub borders and can also be used as flowering hedges. They make terrific accent or specimen plants and can be grown in containers, bringing color to patios and decks.

How to Plant Tropical Hibiscus?

• Set your Hibiscus in the planting hole so that the stem is just at the soil surface. If necessary, add some backfill soil to the bottom of the hole to achieve proper planting height.
• Water well around the plant after planting.
• Spread mulch around the plant to retain moisture in and weeds out. This will also provide winter protection for the roots.

Tropical Hibiscus Care

Watering

• To grow healthy Tropical Hibiscus with plenty of colorful blooms, they must be well watered.
• Never allow the soil to dry out to the point of wilting. A lack of water will impede both growth and blooming.
• Keep the soil relatively moist, not saturated.
• Water often when the weather is warm and hot. This typically means daily watering when temperatures are 70-80ºF (21-27ºC) or even twice a day in extremely dry conditions, upper 80ºFs and above.
• Water should be directed to the root system, and the foliage should be kept as dry as possible.
• Water each plant thoroughly so that the water soaks through the root zone.
• Placing saucers underneath the containers and filling them with water will also help during the hottest times of the year.
• For plants in the ground, digging a shallow well around the base of the plant is a good trick to make sure water seeps down through the whole rootball.
• During winter, allow the soil to dry out a little more between watering.

Fertilizer

• Tropical Hibiscus are heavy feeders and will benefit from fertilization. Without sustained nutrition, a plant will become stressed from lack of nutrients, and it can take a long time to recover.
• Fertilize regularly from spring through fall, but cut back during winter. You can stop fertilizing completely when overwintering unless you see nutrient deficiencies.
• The easiest way to feed your Hibiscus is with a water-soluble fertilizer. Use it every time you water or at least once a week.
• Tropical Hibiscus need high levels of potassium as it promotes the best blooms.
• Tropical Hibiscus need very little phosphorus. High levels of phosphorus will slowly damage the plant over time.
• Tropical Hibiscus need a medium level of nitrogen. Too much nitrogen can burn the leaves, and too little nitrogen can stop the Hibiscus growth.
• Ensure your fertilizer includes, at a minimum, copper, magnesium, and iron.
• Ensure not to over-fertilize, as this can cause toxicity and kill your Hibiscus.
• Tropical Hibiscus thrive on well-aged compost. All organic matter is beneficial as it provides nutrients and promotes a healthy balance of organisms.

Pruning / Deadheading

• Deadheading Hibiscus flowers will promote new blooms.
• Pruning improves the shape of your Hibiscus and stimulates vigor and branching (the more branches, the more flowers) while opening up the center to air circulation and sunlight, promoting new flowers.
• Tropical Hibiscus flower on new wood (this year’s growth). They form buds at the end of each branch.
• Prune in early spring as cooler weather gives way to warmth and new growth buds swell. Do not wait for these buds to open.
• Occasional mid-summer pruning can be done on vigorous shrubs, especially in warm climates.
• Prune in late fall if your Hibiscus is planted outdoors in very warm climates where winter freezing is rarely an issue.
• Prune in the fall if your potted Hibiscus is brought into sunny windows inside the house for the winter. It will regrow very quickly and be ready to bloom as soon as you put it back outside in the spring.
• Prune in spring if your potted Hibiscus is brought into a dark place (e.g. basement) for the winter.
• More frequent and lighter pruning may be needed throughout the year for Hibiscus grown indoors.
• While you will be pruning off flower buds in addition to the foliage, the payoff is that you will get far more flowers: from each pruned stem, 3 new stems will grow in its place.
• Remove any dead wood, misshapen, or sick branches.

Propagating

• Tropical Hibiscus can be propagated by semi-ripe cuttings in late spring or early summer.
• Take 4-6 in. cuttings (10-15 cm) from the strongest shoots available. Use a sterile, sharp cutting tool to cut the stem. Cut below the node at an angle of about 45º and remove any leaves.
• Dip the cut ends in a rooting hormone compound, and stick them in a small pot filled with a light potting mixture.
• Keep slightly moist and place in a warm spot, away from direct sun.
• Put a clear plastic bag over the plant to preserve moisture and retain heat while it establishes roots.
• After 6-8 weeks, they should develop a good root system and be ready for transplanting.

Pest and Diseases

• Hibiscus are not bothered by many pests or diseases.
• Keep an eye out for aphids, scale, mealybugs, thrips, mites, powdery mildew, downy mildew and botrytis.