Dwarf Hibiscus Bonsai Care Guide
Hibiscus is a genus of flowering shrubs native to warm temperate, subtropical, and tropical regions all over the world. It is a large family, containing several hundred varieties. Hibiscus syriacus and Hibiscus rosa-sinensis are the most common cultivars used in the United States.
It's worth noting that most "Dwarf Hibiscus" are simply regular hibiscus that are treated with growth regulator to keep them small. In recent years, however, a true dwarf species was developed from the Hardy Hibiscus; they are called Hibiscus moscheutos 'Luna' and come in four colors – 'Luna Red', 'Luna Rose', 'Luna Pink Swirl', and 'Luna White'. While most hibiscus reach a height of 3-5 feet as landscape plants, 'Luna' is compact, coming in at closer to two feet.
These gorgeous, showy plants come in almost every color imaginable – from yellows and purples to reds and oranges, including many multi-colored patterns. The leaves are palmate, toothed, and grow up to four inches in length. Bloom size varies among cultivars – some varieties develop flowers up to a foot across, earning them the moniker "dinner-plate hibiscus". The trunk tends to a light grayish.
Hibiscus syriacus 'Lil' Kim' is a particularly good variety as a dwarf bonsai, with small white flowers that have a red "eye" in the middle, and a longer bloom life than most at three days.
The important thing to know when you purchase your hibiscus is whether it is a hardy (perennial) or tropical. Tropical plants have glossy green leaves and blooms that are 3-6" in size, while hardy species have duller green, heart-shaped leaves and up to 12" blooms.
If it's a hardy cultivar, it will not require much special care in winter, although both hardy and tropical plants can be brought indoors when winter temperatures dip below 45° F. If tropical, it will require plenty of light to bloom and protection from cooler weather. Both kinds of hibiscus enjoy hot, sunny days, and can also be indoor bonsai as long as they are given enough light.
Dwarf Hibiscus does not like drought, so it will require frequent watering. Check the soil twice a day to ensure that it doesn't dry out, but don't allow it to stay consistently soaked either. When the bonsai is inside over the winter it will need less water but the air is dryer, so misting is a good idea. A humidity tray may also be used to increase the amount of humidity around the tree.
Flowering plants like regular feeding, and an organic product like fish emulsion or blood meal will contribute to colorful, profuse blooms. In spring and fall a 7-2-7 blend may be applied.
Styles – Dwarf Hibiscus can be trained to nearly any style – go with a traditional upright, or get creative and train the trunk to the side, accentuating the end of the top branch with a large bloom.
When this species is pruned, flowering will halt while the plant recovers new growth. The more aggressive the pruning, the longer it will take for blooms to come back. Lighter, more frequent pruning can circumvent this issue.
Do not prune in late autumn or winter as this kills new growth. Instead, do your trimming in early spring or fall; use sharp bonsai shears/scissors and make your cuts a quarter inch above a bud that points the direction you want your bonsai to grow.
The bark of this plant is delicate so wiring is not recommended. The trunk, however, does thicken easily if planted in a tub.
Hibiscus may be propagated by cuttings placed in plastic pots with perlite. Rooting hormone is usually necessary, and the medium must be kept moist. Place several cuttings in a small pot and keep warm. With sufficient humidity and light your cuttings should set root within several weeks.
This should be carried out when the root system begins to outgrow the pot. Trim any mushy, smelly, or discolored roots and transplant into a container that is no larger than one third bigger than the root mass. Hibiscus tends to flower best if its roots don't have an excess of space.
Insects/Pests & Diseases
Dwarf Hibiscus may fall prey to aphids, whitefly, or Japanese beetles. These pests may be removed by gently rinsing off outside with a hose, or placing them in the tub and showering them clean.
Other potential issues are canker, leaf spot, or flower blight. Leaf spot is not normally serious and should pass once a winter season passes and the weather dries up. If you're concerned about the unsightly nature of the fungus spots on the leaves of your beautiful bonsai, a mild fungicide may be applied.
Inspect your Dwarf Hibiscus bonsai several times a week for signs of insects or other health problems. Proper watering and feeding will contribute significantly to maintaining the health of your plant.