The Root of the Problem
Nursery-grown stock can have problems; here are some
By James Urban, FASLA
James Urban, FASLA
Nursery-grown trees specified by landscape architects can
have serious problems. Many trees are planted with roots that are not suited for
long-term support of the tree, causing decline and death. These problems
include roots too deep below the soil line, kinked roots, girdling roots, and
roots not sufficiently distributed in the root ball. Most of these conditions
are the result of nursery practices that may start during propagation and
continue until harvest, although planting methods can also affect root location
The following assessment of the state of nursery material
suggests a difficult road as we try to implement solutions. Nurseries,
contractors, landscape architects, and other specifiers need to be educated and
accept the need for change. There will be a long period where some contractors,
nurseries, and designers will try to make their own corrections while others
will not. In this situation bidding will be difficult. Making changes will cost
money, and the playing field will not be equal between the contractors and
nurseries making changes and those that are not.
Designers and consumers who buy finished landscapes on a bid
basis will need to be clear in the bidding process about exactly what they
expect and that they intend to enforce new requirements. Without this built
into the specifications, specifiers should not expect the contractor to resolve
problems. Designers and contractors must work together.
Commercially produced trees are significantly different from
trees that develop from seed in nature. Roots are cut off at the time of
transplanting, and other important differences occur during production.
Understanding propagation and nursery production processes is important to
understanding how to specify or select a tree.
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