Specialized Pruning Techniques

Pollarding is a very old, traditional European method of maintaining tree size. It involves annual cutting of aggressive shoots back to the same nodes. This results in the formation of pollard “heads”, which look something like swollen fists at the ends of branches.

Pollarded trees not only stay the same size through time: they develop excellent branch taper (a measure of the ratio of branch length to girth). As a result, pollarded trees are extremely resistant to the breakage that frequently results when Front Range trees are subjected to extreme weather events. The London Plane Trees along the Champs Elysees in Paris are, famously, pollarded.

When practicing round-over pruning, an arborist trains the tops of trees horizontally, and the sides downward, by heading back small diameter branches to laterals that are growing more or less perpendicularly to those branches. This is repeated year after year, until the tree achieves a rounded top and slightly weeping sides. As with Pollarding, rounding-over helps maintain tree size. It is particularly useful in yards where a tree would otherwise grow up into a view that the homeowner wishes to preserve. It can be done in conjunction with Pollard cuts, to achieve a globe-shaped crown on a tree.

Espalier is a method of pruning a tree or shrub into a vertical, two dimensional form. This is usually done against a wall, or along a series of parallel horizontal wires. The branches can be trained into formal arrangements, such as candelabra, fan and palmette, or allowed to grow more informally, at the whim of the pruner. Espaliered trees should be pruned annually, to keep them in scale.

Pleaching is a way of interweaving parallel rows of trees; it may involve creating a living arch over a walkway, or just creating a hedge effect in parallel rows, but with the stems pruned bare to a uniform height.

One of the signature features of great Japanese gardens is the placement and maintenance of what are frequently referred to as “specimen trees” or “Character Pines” (they are also commonly and incorrectly referred to as “bonsais”). This cultural practice results in preserving a “human” scale to trees in the garden; it also achieves tree architecture – frequently leaning, usually asymmetrical and thin enough to reveal inner structure – that makes trees look older than they are.

The best specimen trees in Japan are hundreds of years old; many of the ones found in Boulder County landscapes –some very old, too– are dwarf sized Ponderosa Pines that were “collected” from mountain forests. They can also be trained from a young age to affect the same look. Overgrown old Pfitzer Junipers take surprisingly well to this style of pruning: Many homeowners have allowed us to clean and thin them out to achieve a new look, without having to start over by removing/replacing.

In order to keep them in scale, Japanese garden trees need to be maintained by skilled pruners on a frequent basis – usually annually, and in some cases twice or more times per year. We have studied and worked with Harold Sasaki, a world famous bonsai artist and garden tree pruner out of Applewood, CO, for the better part of two decades and have worked on unique trees in some of the finest Japanese gardens in the area.