Choosing and Preparing a Location
Hardy hibiscus do best in medium to wet soil that drains well. The soil shouldn’t be too heavy; however, these plants will not do well in sandy, dry, or poor-draining soils.
Therefore, if the soil in your garden is sandy or drains poorly, mix in a few inches of organic compost before planting your flowers.
In cooler climates (zones 4 to 6), hardy hibiscus will do best when planted near south-facing wall, where they will receive plenty of sunlight and are protected from wind.
If you live in a warmer climate, a location that receives about 6 hours of sun a day would be ideal; however, do note that if they receive too much shade, their stems will likely be long and leggy and their blooms may not be as healthy or they may not produce any blooms at all.
Watering
In the wild, hardy hibiscus grows in swamp areas. While cross-breeding has reduced the water requirements for many varieties, they do still need to receive adequate water in order to thrive.
Make sure that the soil remains moist; however, you don’t want to water the plant too much, as doing so could lead to root rot.
Smaller plants with less leaves don’t need to be watered as often as larger, leafier plants. During the growing season, hardy hibiscus should be watered on a daily basis.