Gardenia Bonsai Tree Care Guide
Gardenia is a genus of flowering shrubs and small trees known for its showy, sweet scented flowers. It is native to subtropical areas of South Africa, southern Asia, Australasia, and Oceania. In its natural habitat the plant may grow to anywhere between two and twelve feet tall, and just as wide, depending upon the variety.
The most common cultivar is Gardenia jasminoides, also known as Cape Jasmine. While this species can be a challenging bonsai to grow it still enjoys popularity among enthusiasts.
The foliage is glossy and dark green, with leaves growing opposite or sometimes in whorls of three to four. The flowers, which are one of the main attractions for enthusiasts, are waxy and white, turning to a creamy yellowish.
Some varieties produce a very strong scent, so those with allergies or other sensitivities may want to steer clear just in case.
The trunk of a mature gardenia is smooth and brown.
As a tropical, Gardenia jasminoides requires a humid, warm environment, with a daytime temperature between 68° and 74° F and a nighttime temperature no lower than 60° F. This plant requires at least three to four hours of sunlight exposure daily, so if kept as an indoor bonsai in temperate climates it should be placed in a south-facing window or put under grow lights for some of the day.
During the summer, and in warm climates, Gardenia can be kept outside.
This beautiful flowering plant needs frequent watering when exposed to a lot of sunlight. It will likely require more water than most typical bonsai, as tropical need to be in consistently moist, well-draining soil; drying out completely may kill the plant or lead to damage at the least. It is a good idea to elevate this plant on a bed of pebbles or similar material so that it does not sit in water and become prone to root rot. Misting is not recommended as the leaves may retain moisture that leads to the development of fungus.
Gardenia loves acidic conditions, so should be fed with an acid fertilizer monthly throughout the growing season, from spring all the way through fall. If the leaves start to turn yellow with green veins, add some chelated iron to reverse the process of chlorosis.
Styles – this tree may be shaped into most bonsai styles and takes particularly well to broom, cascade, umbrella, formal upright, and informal upright.
Pruning should be done after the blooming season is over. Locate unbranched, long growths and prune them above a leaf bud. Do not be too aggressive in the number of branches you prune, as the flower buds form at the end of these limbs.
Remove all dead blooms and foliage. Defoliation may be performed on this plant in order to encourage vigorous blooming. It's best to do a partial defoliation, removing no more than 2/3 of the growth.
Wiring may be carried out in late winter or spring. This should be done carefully, bending very gradually in multiple locations along the branch to avoid breakage. Repeat this process every three days or so. Check the wires frequently to be sure they aren't cutting into the bark due to growth.
Gardenia roots readily by cuttings. Take a six inch length from a healthy, mature plant and place in a jar of water. Roots will develop in a short time. Once the root system has developed to the point of being able to support the cutting, plant in organic soil made for acid-loving plants and keep moist until established.
This should be carried out about every other year, during spring or winter. Root pruning may be done during this time but keep in mind that Gardenia does not tolerate aggressive root pruning. You should only remove a maximum of ten percent of the root mass, concentrating on roots that seem discolored or mushy. Transplant into a soil mixture that is heavy in organic matter.
Insects/Pests & Diseases
Gardenia may suffer from aphids or mealy bugs. Aphids may be washed off with a solution of liquid soap in warm water, sprayed on until runoff occurs. Rinse with a spray of clear water. If mealy bugs are seen on the leaves of this plant, wipe them off manually then spray the bonsai with neem oil.
Another threat to this species is sooty mold. This is a fungal disease that affects the foliage of the plant. It isn't fatal, but it can stunt growth because of the ugly black patches that interfere with photosynthesis. Sooty mold feeds on the "honeydew" produced by aphids, so controlling these pests with keep sooty mold at bay.