Although they often thrive in completely sunny locations, hibiscus do not actually need as much direct sunlight as is commonly thought. Our own experiments have shown that 2 hours per day of direct sunlight is enough to stimulate blooming, even indoors through a window! However, if the hibiscus receive insufficient sunlight you will end up with pretty green bushes without blooms.
Hibiscus do best with the proper balance of sun, heat, and water. Sunlight and temperature are 2 factors that work in opposition to each other. In other words, if the temperatures are high sunlight should be reduced. If sunlight is high, lower temperatures are better. When both sunlight and temperatures are high water needs go way up and when either or both sunlight and temperature go down so do the water needs of the hibiscus.
OK, so what does this mean in practical terms?
Let me give you some common examples:
Along coastal California where the temperatures are often quite mild, it is best to provide a location with lots of sun. We have seen even the most fancy of modern varieties of hibiscus thrive in all day full sun and in fact grow them that way in our own yard.
In the hot and dry conditions of inland California or southern states like Arizona it is best to grow hibiscus in a location that has a lot of shade but some direct sun.
In states that are hot and humid like Florida or coastal Texas, a location that is partly shaded is often best, although frequent clouds and rain reduce the need for shade and hibiscus can be successfully grown in full all day sun.
If your preferred area is on a porch with only morning or afternoon exposure to direct sunlight, that is just fine. A growing location near trees that allow filtered sun plus some direct sun is also good for hibiscus. –Birdy.
