Improvement status: Cultivated material
Seeds per packet: ~20
BOTANICAL SAMPLE - NOT GERMINATION TESTED
Life cycle: Perennial
Ginkgo trees are living fossils. They are the only species in their genus, which is the only genus in its family (Ginkgoaceae), which is the only family in its class (Ginkgoopsida), which is the only class in its phylum (Ginkgophyta). Practically the only thing it has in common with other plants is that it is a plant. There are only five living types of seed-bearing plants, and ginkgo is itself one of them (most of the others have innumerable examples). Its near relatives are only known in the fossil record, and the species itself is believed to be relatively unchanged for over 200 million years. It also has a very large and complex genome, with more than three times the DNA nucleobase "letters" as the human genome (10.6 billion compared to our 3 billion). Like humans and cycads, the ginkgo's closest living plant relatives, the reproductive system of these plants involves motile sperm (only discovered in 1896 by Japanese botanist Hirase Sakugorō). Europeans first encountered gingkos as revered specimen trees in temple gardens in Japan, though it is considered only to be native to central China in the modern era (after having once had a near global range in prehistory). There is some debate about whether or not ginkgo only exists because people brought it into cultivation, but experts believe a population or two in central China are likely truly wild. Interestingly, though China has had a written history for at least 3000 years, mentions of ginkgo only begin 1000 years ago, indicating that its spread around East Asia likely is a relatively recent phenomenon.
But while gingko is a fascinating tree in the abstract, it is also a wonderful and useful tree with a variety of uses. First and foremost, it is a food plant. The heart of a ginkgo seed is a nut that tastes like no other. It is good prepared in a variety of ways, roasted and salted in shell to boiled in a sweet barley porridge. In Japan they are a common bar snack, like pretzels. They are something of a soft nut, more like a chestnut than a walnut, and they have a complex flavor. Some people have an adverse allergic reaction to ginkgo, and the seeds are said to contain toxins, so should only be eaten in moderation. It is also considered a medicinal plant, with the nuts eaten in China as an aphrodisiac and for memory. In the US, ginkgo leaves have become a common supplement for memory and brain health, through scientific studies into this property have been inconclusive.
Ginkgo is most widey grown as a tough-as-nails ornamental plant, especially for street plantings. It seems to be able to handle whatever humans throw at it, so has been planted in cities around the world. In addition to its unique fan-shaped leaves, it is noted for the striking yellow color the leaves become in the fall — and for their propensity to drop all one day, leaving a striking yellow carpet underneath each tree. Ginkgo is a dioecious plant, meaning there are both males (which produce small pollen-bearing cones) and fruit-bearing (nut-bearing) females. The females are largely no longer used as street trees, because the fruits are notoriously messy and smelly. But since the nut-meat is so valued, you will often find people foraging beneath the odd female street tree looking for nuts. It's believed the unpleasant smell of the fruit was attractive to a long-extinct animal that coevolved as a dispersal agent for ginkgos (yes, it could have been a dinosaur). Because of the smell, we recommend planting any female ginkgo trees away from places where people live or regularly congregate. The seeds germinate most readily after a period of warm-then-cold moist stratification. We have not done it ourselves, so we recommend searching online for instructions and examples, and trying a couple different methods. These seeds were produced for us by Aaron Parker of Edgewood Nursery in Maine.
GROWING TIPS: Seeds should be kept damp and cool until March or April, then planted 1/2” deep. In northern location you may want to grow in containers for the first year so seedlings can be protected over their first winter. Direct sowing also works fine.
Ginkgo grows slowly at first, but once established they tolerate drought, soil compaction, urban pollution and other difficult conditions. Ginkgo is dioecious, with each plant making either male of female flowers, so if you want seed production plant at least 3 seedlings to ensure you get at least 1 male and 1 female, planting extra seedlings and removing some of the males is a good idea for a larger plantings.