Hibiscus is a lovely tropical plant best known for its large, bright red flowers. But in fact, the hibiscus comes in different varieties that include deep-coloured, variegated foliage that is quite striking. There are also hibiscus plants whose flowers change colour as the day advances, affected by several factors: temperature changes, hours of daylight and other variables. The type of hibiscus you choose, and the environment and care you provide, will affect the sort of colour variations you get. Also, environmental or plant health changes greatly affect the three basic hibiscus flower pigments, which in turn alter flower colour.
If you want to grow a tropical hibiscus, you'll need full sun, with partial shade. Its soil needs are acidic, but slightly alkaline. USDA cold hardiness zones 10 or 11, such as Florida, are the best environment.
For a variegated sea hibiscus, or mahoe, a seaside or mangrove area is a suitable environment, such as that found in USDA zone 10 or possibly warm zone 9. You can let this hibiscus grow tall--20 feet--or trim and prune it to maintain it as a shrub. It's drought tolerant and has low water needs.
The hardy hibiscus, Hibiscus moscheutos, is pretty standard. Its blooms can be bicolored or have dark veins. Hardy hibiscus are more tolerant; they are native to marshy areas in the United States and are late bloomers, flowering in May or June.
Variegated Hibiscus Foliage & Flowers
The Hibiscus rosa-sinensis "Cooperi," also known as the variegated hibiscus, is tropical, with multicoloured foliage, including splashes of white, pink, green, burgundy or red. Its flowers are bright red, but the leaves are distinctive in their wide-ranging colour mix.
Another hibiscus plant with variegated colours is the Hibiscus tiliaceus variegate, or variegated sea hibiscus. In Florida, they call this the mahoe hibiscus. It grows quickly and can reach up to 25 feet in height unless pruned. Both leaves and flowers are tricolour. Flowers are yellow in the morning and then gradually turn red-orange later in the day.
Three pigments rule hibiscus flower colours: carotenoids, anthocyanins and flavonols.
Carotenoids, the most stable pigment, hold their colour, which is the warmer tones (yellow, orange, red). The hotter the weather and brighter the sun, the more carotenoids produce, for warmer and deeper colour in your hibiscus flower. Look for rich orange and red colours in summer heat; with cooler weather, the colours will soften because carotenoid production drops off.
Anthocyanins are unstable, and this pigment holds the cooler shades (blue, purple, pink, deep red and even black). Any environmental shift will be reflected in blue shade changes. Varying levels of acidity and alkalinity in hibiscus' flowers can alter the blues to reds in hibiscus. With a temperature drop, the hibiscus produces more anthocyanins and its colour reddens.
Flavonols, like anthocyanins, get a boost in healthy plants and cold weather, and decrease with heat and bright light. (In fact, anthocyanins and flavonols are two different types of flavonoids, so their colour changes are similar.) The main colour of flavonols is a pale yellow, which shifts into white. Its yellow will lighten to white with warmer weather, and deepen in cooler weather and less light.