Ginkgo biloba - the tree that fed the dinosaurs

Jun 06, 2012

by Judy Wall, Lanark county Master Gardeners

Millions of years ago, dinosaurs as big as houses ate their way through ginkgo groves in North America, munching on the trees’ leathery fan-shaped leaves as they went. Today, we only know about dinosaurs because of their fossils, but the ginkgo tree is still with us. The ginkgo became almost extinct when continents shifted and glaciers bore down during the Ice Age. But about 300 years ago a specimen was discovered in a Japanese temple garden. The ginkgo tree which was cherished by gardeners in Japan, was reintroduced to Europe, and reached North America again about 1800. It was a homecoming for the tree after millions of years.

Besides its ability to thrive in cramped conditions, the ginkgo is virtually immune to pests and diseases. It tolerates smog and city conditions, too. In the fall after the leaves have turned golden yellow, the ginkgo sheds all its leaves at once, rewarding the gardener with a one-time rake-up job.

Ginkgos are dioecious, meaning male and female flowers are on separate plants. Male trees have catkins that flower in spring. Female ginkgos have tiny greenish seed-bearing flowers that turn into plum-like fruit. As these ripen and fall, they rot, giving off an unpleasant smell. So, be sure to select a male tree. Sex is hard to determine until it begins to fruit – in about ten years.

Mature trees can reach nearly 80 feet and have a pyramidal shape when young. They are hardy in our area and nurseries should have them available to gardeners wanting an interesting garden specimen.

It is possible to grow your own ginkgo tree from a cutting taken during the growing season. Pull a new shoot away from a heavier branch so that a “heel” from the older wood is attached. Cut off lower leaves. Fill a container with a mixture of peat moss and sand and moisten it well. Poke a hole in the centre of the soil about 2” deep. Dip the cutting in a rooting hormone for semi-hardwood cuttings and insert your cutting in the hole. Firm the soil around it. Place a stake in beside the cutting. Enclose your pot and cutting with a clear plastic bag and secure it to the top of the stake. Leave the mini greenhouse outside in bright light but away from direct sunlight. Condensation will form inside the bag. After about six weeks, start opening the bag for short periods, gradually exposing it to outdoor conditions. After about a week, remove the bag and water plant as required. On a cloudy day you can then transplant it to its new location. Water frequently, especially in dry weather.