Starting a Ginkgo Tree From Seed
I can't resist collecting seeds.
Sometimes I venture out, a paper bag or glass jar in hand, and collect them from our yard.
More often, I pick them up wherever I happen to be, so it didn't surprise my husband too much when I stopped under a row of shedding Gingko biloba trees on our way into a movie theater.
Have you ever collected seeds?
Collecting Ginkgo Seeds
"Look, ginkgos!" I cried, grabbing a handful of fat, sticky seeds from the sidewalk.
Landscapers generally use male ginkgos because they don't drop ginkgo fruit, which reputedly smells like rancid butter as it rots, but whoever installed the landscaping outside the AMC had planted a few females trees as well.
Ginkgos are long-lived trees, the oldest one recorded at 3,500 years old. Most, however, only make it to one thousand.
These trees had to be at least 20; female ginkgos don't produce fruit until they're at least that old.
The acids in gingko fruit are similar to urushiol, the skin irritant found in poison ivy and poison oak. Although I didn't have a reaction, to be on the safe side, you may want to wear gloves when collecting it.
A New Windowsill Project
"They're the oldest tree species on earth," I told Dennis, stuffing seeds into my pockets. "They're older than the dinosaurs! Scientists call them living fossils."
The look on his face was priceless— a blend of embarrassment, humor and tenderness (or at least I hope that's what it was).
He wore the same expression the next day when, while hiking historic St. Mary's City in Southern Maryland, we came across more ginkgo trees, and I grabbed up more seeds— and decided it was fate: I would make starting ginkgo trees from seed my new windowsill project.
Ginkgo biloba are commonly called maidenhair trees because their fan-like leaves resemble the leaflets or pinnae of the maidenhair fern.
Preparing the Seeds for Germination
That afternoon when we got home, I sorted the seeds I'd collected and washed them, scrubbing off the sticky fruit as best I could.
Then I set them on a clean, dry cloth to dry and began researching how to start ginkgos from seed.
All the sources that I read agreed on one essential step in the germination process: stratification.
The ginkgo tree is from the era of dinosaurs, but while the dinosaur has been extinguished, the modern ginkgo has not changed. After the atomic bomb in Hiroshima, the ginkgo was the first tree that came up. It’s amazing.— Koji Nakanishi, Professor, Columbia University
Stratification refers to artificially reproducing the moist, cool conditions some seeds need in order to germinate.
A few of the seeds I simply cleaned and tossed into an old glass spice jar, then stored in the refrigerator.
Before beginning, I made sure my pots and seeds were as clean as possible to prevent mold during germination.
I chose clay pots for their porosity, and scrubbed them in hot, sudsy water. Then I set them on clean towels to dry. (Plastic pots and baggies purportedly work well too.)
After reading a study about sterilizing seed for commercial nurseries, I also soaked the ginkgo seeds in 3% hydrogen peroxide for four hours. Then, before planting, I rinsed them with water.
Because ginkgo seed coats are hard, I opted to scarify some of the seeds, too, just to see how it would impact their germination.
Using an emery board, I scratched the seed cases to allow moisture to more easily penetrate them.
Other methods for scarifying include rubbing seeds with sandpaper, nicking them with a knife, and soaking them in hot water or a concentration of sulfuric acid.
The Growing Medium
Next, I prepared the growing medium.
The Master Gardener Handbook recommends peat moss, vermiculite or sand. The idea is that the medium should retain moisture without holding so much water that it causes rot.
I didn't have any of recommended mediums on hand per se, but I did have potting soil for cacti in the garage, a blend of peat, sand and perlite, so I used that, first filling the pots with the mixture, then adding the seeds and covering them with about a half-inch of the medium.
Moisture & Cold
Then I watered the pots multiple times, allowing them to drain after each watering.
Because the potting medium was fine and flyaway, I found it easiest to pour the water into the pots with a cup.
Finally, I placed the pots in plastic bags, secured the bags with rubber bands and set them in the refrigerator.
The Impatient Wait
There they will stay for about ten weeks, at which time I'll move them to the windowsill and wait impatiently for signs of life.
I'll keep you apprised of their progress.
I'm interested to see which seeds germinate the quickest. With any luck, I should have photos of some lovely green sprouts to share this spring.
How Kew Gardens Starts Ginkgo from Seed
While researching Ginkgo biloba, I ran across an interesting article on the Kew Royal Botanic Garden website. According to the article, Kew starts its own ginkgo seed each year, first removing the flesh from collected fruit, then stratifying the seed by placing it in cold storage.
In the spring, the seed is sown in well-draining compost in one of Kew's greenhouses, and germinates in eight to ten weeks.
The following spring, when they're good-sized seedlings, the trees are planted in Kew's Arboretum Nursery field. At about two years old, the ginkgos are ready for planting in the gardens proper.
Featuring "The Old Lion" Ginkgo Tree at Kew
© 2017 Jill Spencer