Nancy Tierney, Extension Master Gardener, Anoka County
As our urban forests are succumbing to Dutch elm disease, oak wilt and emerald ash borer, you may want to diversify and consider planting a Ginkgo tree. Ginkgo trees adapt well to most environments. They are relatively disease free, low maintenance and pest free. They tolerate heat, air pollution and salt; everything desired in a hardy, suburban friendly tree.
The beautiful fan shaped leaves of this tree make it one of the prettiest trees of all time. The vibrant green leaves are small, about 3" across, and are far less messy to clean up in the fall than larger oak leaves. While other trees have dropped their leaves in the fall, the Ginkgo tree leaves turn a brilliant shade of gold.
Ginkgo is a deciduous conifer native to China, dating back 200 million years and often known as maidenhair tree. A botanical dinosaur, this hardy tree is the only tree known to survive the Hiroshima attack. Ginkgos are dioecious trees having separate sexes, some trees being female and others being male. Trees sold in nurseries are male plants, as the female tree produces seeds. While a tree may not produce seeds until it is 20-35 years old, the seed coating is foul smelling and the seeds can be a nuisance on the ground. While slow growing, when mature, ginkgo trees reach up to 100 feet tall and have a canopy between 30 and 50 feet wide.
Ginkgo trees are easy to grow and adapt well to most urban environments. They prefer moist, sandy, well-drained soil but will tolerate a wide range of soil conditions. They grow in zones 4-9. Saplings may need to be staked and are easily transplanted once they attain some size. The Ginkgo tree grows a very long tap root. When planting, it is important to dig the hole deep enough for the tree root ball. Avoid air pockets in the soil by half filling the hole with soil after setting the root ball, then water thoroughly. Allow the soil and roots to soak up this water before you fill the hole, until almost level with the rest of the ground. Then water again and leave it overnight to settle. Water a third time so the water pools around the base of the tree. This should eliminate air pockets in the soil. This tree is amazingly easy going and will tolerate almost anything, preferring full to partial sun. Water regularly the first three years of life, allowing the soil to dry, but not stay damp. While fertilizing is not required, you can give it a boost in the spring with a slow-release balanced 10-10-10 fertilizer. Mulch in the summer to preserve moisture and before winter to protect the roots from cold. Ginkgo does not require pruning. Over watering is the most common cause of failure to survive.
This beautiful ornamental tree will soon become one of the most fascinating trees in your garden or yard. With minimal effort and care, you will have a stunning tree resulting in many years of shade.