Hibiscus plants stand out with their large, trumpet-like flowers. They come in various colors depending on the variety.
While dozens of species exist, Hibiscus mainly falls into two categories: hardy outdoor deciduous shrubs (mostly Hibiscus syriacus) and indoor evergreen plants (mostly Hibiscus rosa-sinensis).
Indoor hibiscus blooms from May to October, but keeping them healthy requires the right conditions. In contrast, hardy outdoor varieties need minimal care. They will reward you with stunning floral displays for years if they receive plenty of light.
How to Plant Outdoor Hibiscus
When grown in the right conditions, Hardy or Outdoor hibiscus plants thrive with minimal effort. Once established, they quickly fill a space each season, though they may take a while to emerge in spring.
When to Plant
Plant hardy Hibiscus in spring after the last frost to give it the best start. If you prefer growing from seeds, start them indoors about 12 weeks before the expected last frost date.
Where to Plant
Plant hardy hibiscus in a full-sun location with well-drained, acidic soil enriched with compost. Provide some shade to protect it from intense midday sun in hot climates. While Hibiscus can tolerate partial sun, it may produce fewer flowers than those grown in full sunlight.
Spacing, Depth, and Support
Space hibiscus plants 2 to 3 feet apart, as they can grow up to 72 inches tall and 3 feet wide. Sow seeds about 1/2 inch deep in well-draining soil. Maintaining high humidity and warmth during germination.
When transplanting, keep the base of the stem level with the soil line. Adjust the planting height by backfilling soil into the hole, which should be as deep as the planting container and two to three times wider. Once positioned, fill the hole with fresh soil.
Hardy hibiscus typically grows sturdy, has woody stems, and rarely needs support. However, a grow-through support grid can help train the stems to stay upright if they become limp or leggy due to insufficient light.
Outdoor Hibiscus Care
Here are the key requirements for outdoor Hibiscus care:
- Plant in a full-sun location; if kept in partial sun all day, it may become leggy.
- Use acidic, well-draining soil enriched with compost for optimal growth.
- Water regularly, providing at least 1 to 2 inches weekly, with daily watering in hot weather.
- Bring indoors or protect with winter wraps when temperatures drop below freezing.
- Apply fast-release fertilizer weekly or slow-release fertilizer three times a year, but avoid fertilizing during winter dormancy.
Light
To help your hardy Hibiscus reach its full blooming potential, ensure it gets at least six hours of full sun daily. In hot and dry climates, provide occasional relief from intense afternoon sun by planting nearby leafy plants for shade or choose a location with light afternoon shading.
Soil
Hardy Hibiscus thrives in moist environments. It is perfect for wet areas where other plants may struggle. It also grows well near water features and ponds. These plants need organically rich soil, so if your landscape soil lacks organic matter, amend it with compost before planting.
Water
If you can’t plant hardy Hibiscus in a naturally moist area, ensure it receives adequate water without overwatering. These plants are typically thirsty and require watering of at least 1 to 2 inches per week, sometimes daily. Smaller plants with fewer leaves need less water than larger, leafy ones. Check soil moisture by feeling an inch below the surface. If it’s dry, it’s time to water.
Temperature and Humidity
Hardy hibiscus plants may resemble tropical flowers but can withstand cold temperatures. They bloom best in temperatures between 65 and 75°F. Before temperatures drop to 32°F, bring them indoors to prevent frost damage, but watch for low humidity, which can dry them out quickly. If left outdoors, protect them with winter wraps like burlap or tarp to shield them from harsh winds.
When overwintering indoors, mist the leaves every day or place pots on pebble trays filled with water to maintain humidity. As the water evaporates, it increases moisture around the plant. A small space humidifier can also help keep humidity levels stable.
Fertilizer
Hardy hibiscus plants require regular feeding. Apply a diluted liquid fertilizer once a week or use a slow-release fertilizer three times a year, once in early spring, again after the first bloom, and finally in mid-summer.
Pests
Hibiscus can occasionally attract whiteflies or aphids. To remove these pests, spray them with a strong blast from a garden hose or apply insecticidal oil.
Coppery-green Japanese beetles may also feed on Hibiscus. To remove them effectively, knock them into a can of soapy water or use a handheld vacuum.
FAQs
What’s the difference between hardy and tropical Hibiscus?
Hardy hibiscus can survive winters outdoors, though it dies back to the ground during dormancy in cold weather. In contrast, tropical Hibiscus must brought indoors for the winter to survive.
Can hardy Hibiscus grow in partial shade?
While hardy Hibiscus can tolerate partial shade, it won’t bloom well without sufficient sunlight. Even an extra hour or two of direct sun can help increase blooms.
Can hardy Hibiscus grown indoors as a houseplant?
No, hardy Hibiscus is best left outdoors. Without full sunlight, it won’t produce blooms.
