Ginkgo Biloba Bonsai Care Guide
Ginkgo biloba – also known as the Maidenhair Tree due to the similarity of its leaves to the pinnae of the Maidenhair Fern, is a native to Japan and a long revered specimen in Japanese culture due to its medicinal properties. This tree is the only remaining survivor of its order, Ginkgoales. Fossils place its origin as far as 270 million years back, and it was thought to be extinct in the wild until the 1890s when a Japanese botanist discovered surviving Ginkgo sperm.
This fascinating specimen has been the subject of much speculation and change in scientific opinion. It used to be considered a conifer, however current scientific evidence indicates it is much more similar to cycads (like the Sago Palm), which are more fern or palm-like. Most botanists now place Ginkgo, which is a true gymnosperm, in its own classification.
The "rediscovery" of Gingko was possibly amusing to some in Asia, as they had never "lost' the species. There is rumored to exist a 3000-year-old specimen in the Shandong province of China, however this has been difficult to confirm. Many of the trees in the Tian Mu Shan Reserve in China are said to be over 1000 years old. These trees may reach 75 feet in height.
Ginkgo is easily recognized by its columnar shape and beautiful double-lobed, fan-like leaves that turn yellow in autumn and eventually drop. The pale brown to gray bark is fissured and becomes even more deeply furrowed with age. The bark is very delicate and easily damaged – an irony considering that this tree is also known for its astounding hardiness. A number of them survived the Hiroshima bombing in WWII and are standing to this day, a true testament to their nickname – "living fossils".
Even though this is the only living extant species in its family there are multiple cultivars, many suitable for bonsai:
- 'Autumn Gold' – a broad, symmetrical male variety with bright fall color
- 'Variegata' – has leaves with white-yellow stripes
- 'Laciniata' – possesses deep divisions in the leaves
- 'Chichi Icho' – a favored variety for its smaller leaves and textured bark
- 'Aurea' – has leaves of yellow in summer
As a bonsai this deciduous tree still requires a period of dormancy and should be kept outdoors. In the shallowness of a bonsai container, however, the moisture-rich roots will need protection from freezing. Light should be full sun to partial shade, with some protection offered to younger plants in full summer sun.
Ginkgo bonsai are fairly thirsty during the growing season, but the roots should be kept barely moist during winter to help protect them against frost damage.
Fertilizer should be balanced, and diluted to half-strength, administered every two weeks throughout spring and summer and then again in the beginning of September and October.
Preferred Styles – As a bonsai this tree is best kept in formal or informal upright, allowing its natural column shape to shine. The leaves are relatively large and do not take well to reduction. A small amount of reduction may be achieved through the combination of closely controlled watering practices and confinement in the bonsai pot, but these results are negligible.
The bark does not heal from cuts – whether concave or flush – so pruning should be done by leaving a small stub of the branch, and then gently removing the dried remains the next year. Most of the shaping will be done by way of pruning, reducing each cluster in the desired areas to two to three leaves.
Wiring is not ideal. Very fine bonsai wire may be used to do minor redirection in spring to fall, but this must be done very gently due to the delicate nature of the bark. Some enthusiasts find that girdling the tree can stimulate the production of aerial roots.
Ginkgo is dioecious, meaning it produces separate male and female trees. Bonsai growers tend to prefer male specimens because the seeds of females put off an unpleasant odor. This is most easily achieved via cuttings. Softwood cuttings of about four to five inches can be taken in summer, or you can use hardwood cuttings retrieved in winter. Root in moist, well-draining soil and place in partial shade.
This species should be repotted every year when young, then every three to every five years as it ages. Repotting should be done in spring, with very minimal root reduction. A well-draining soil should be used, with a small amount of added sand and grit.
Insects/Pests & Diseases:
Ginkgo is extremely hardy and resistant to pests and disease. The tree will, in fact, actually have a filtering effect on the air around it and is sometimes used as a city landscape feature precisely due to its effectiveness in this regard.