While most plant tags will tell you that tropical hibiscus takes full sun to partial sun, in reality, if you live somewhere hot and bright, you should go more towards a partial sun location. In Northern climates, however, your hibiscus will probably be happier in full sun. If your outdoor plant is consistently producing hibiscus flowers, it is happy, so keep doing what you’re doing. If your plant is not producing buds and flowers, try moving it into an area that has either more or less sunlight.
For growing in a container, use a well-drained potting mix, preferably one formulated for tropical plants. Outdoors, your soil should have lots of organic matter, and it helps to add a layer of compost.
Tropical hibiscus is a thirsty plant and will thrive and produce blossoms only if it is given enough water. Depending on heat, wind, and humidity, your plant may need to be watered daily, or even twice a day in extremely dry conditions. It may need 1 to 2 inches of water per week. However, the soil must be well-drained. If your hibiscus is dropping leaves, or you’re seeing yellowing leaves at the top of the plant, chances are it’s not getting enough water. If your hibiscus has yellowing leaves in the middle or toward the bottom of the plant, chances are it’s suffocating from too much water.
Temperature and Humidity
The tropical hibiscus plant prefers a temperature between 55 and 70 degrees Fahrenheit. Heat over 85 F can result in dropping buds and leaves. It can be killed by even a few nights below 50 F, so move it inside if the temperature dips below 55 F.
If you live in a northern climate, it is possible to overwinter hibiscus indoors, if you can provide two to three hours of direct sunlight daily. Your plant will need less water in the winter, but the dry indoor heat of winter is hard on tropical plants, so you will need frequent shallow watering as well as daily misting (if the air is dry). If you see any buds, remove them—you don’t want your hibiscus to flower in the winter. In the spring, cut the plant back and put it outside once the nighttime temperatures are consistently above 50 F.
When you buy a potted hibiscus, it likely has a slow-release fertilizer mixed into the soil, so it will not require much feeding in the first few months. After that, regular feeding with a diluted fish emulsion fertilizer will keep it blooming vigorously.