Transplanting is a delicate process that ideally occurs during dormancy, at the beginning or end of the growing season. In the Arnold Arboretum’s nurseries, we use traditional methods to ball and burlap our field-grown trees. To preserve the proper ratio between roots and shoots, we measure the diameter of the trunk: for every inch, we need a minimum root-ball diameter of fifteen inches. Because we cannot input every factor into an equation, we also exercise judgment, accounting for the tree’s height and the anatomy of its root system.
Once we have determined the diameter, we sever the roots with a sharp spade and excavate a trench. The root ball should be deep enough to ensure that taproots are retained—at least 65 percent the diameter. We shave away excess soil to minimize transport weight. The exposed root ball is wrapped with burlap and secured with sisal, using a drum-lacing pattern. We carefully rock the tree, freeing it from the soil below. At this point, the tree is ready to go.
15:1
The proper ratio between the root-ball and trunk diameters.
65 percent
A root ball must have a depth of at least 65 percent its diameter.
Chris Copeland is Greenhouse Horticultural Technologist at the Arnold Arboretum.
From “free” to “friend”…
Established in 1911 as the Bulletin of Popular Information, Arnoldia has long been a definitive forum for conversations about temperate woody plants and their landscapes. In 2022, we rolled out a new vision for the magazine as a vigorous forum for tales of plant exploration, behind-the-scenes glimpses of botanical research, and deep dives into the history of gardens, landscapes, and science. The new Arnoldia includes poetry, visual art, and literary essays, following the human imagination wherever it entangles with trees.
It takes resources to gather and nurture these new voices, and we depend on the support of our member-subscribers to make it possible. But membership means more: by becoming a member of the Arnold Arboretum, you help to keep our collection vibrant and our research and educational mission active. Through the pages of Arnoldia, you can take part in the life of this free-to-all landscape whether you live next door or an ocean away.