Need information on how to lightly trim back a Gingko tree that is a bit too close to a structure. The tree is healthy but a small part of it is beginning to strike a wall which may eventually damage some branches. The tree is about 20 ft tall and 15 feet wide and is evenly shaped.
Thank you for contacting the Toronto Master Gardeners with your question about your Ginkgo biloba tree.
Ginkgos (sometimes known as Maidenhair Tree) are an ancient tree from China related to conifers. They are long lived and generally do not need a lot of pruning. Before pruning your Ginkgo you must know it’s growth pattern. There are different varieties of ginkgos with different growth characteristics.. Each variety of gingko has it own natural shape. For instance, some Ginkgos have a columnar shape, the trees grow up in a narrow, column-like shape. Other varieties grow out more and have a pyramidal or umbrella shape.
There are a couple of rules of thumb that apply to removing tree branches: first, don’t remove more than 1/3 of the tree canopy, and much less than this for a mature tree, remove only 10-15%. And second, 50% of the tree canopy should be in the lower 2/3 of the tree, to protect the tree against damage during a wind storm. In addition, removing branches means removing leaves, and removing a large amount of foliage significantly reduces a tree’s ability to provide food for itself via photosynthesis.
The best time to trim your Ginkgo is when the tree is dormant-late fall, winter or early spring (before budding). Usually the majority of the pruning you will do for a ginkgo is while the tree is still young and establishing its shape. Once the tree is mature, the only trimming you need to do is to remove dead branches or weak or broken limbs. If you must trim your Ginkgo make sure to trim the tree evenly all around so that you maintain the overall shape. Make sure to remove any diseased, intersecting shoots.
You may wish to consult a certified arborist. To find a certified professional arborist to help you with a tree problem, visit the International Society of Arboriculture’s searchable database here