Elisabeth C. Miller Library

PAL Question

PAL Question #634

Answer:

Pruning Leyland Cypress (x Cupressocyparis leylandii) to look like a hedge can be a challenge.

Topping is not a recommended method for controlling trees, because it often
causes them to grow faster (unless they are topped mortally) and thus must be
done repeatedly and expensively, and also because it weakens the tree, which may
cause it to drop limbs, rot, or blow over more easily. The group Plant Amnesty has a great deal of information about why one should avoid topping.

However, topping may be less
harmful for x Cupressocyparis leylandii than for other plants, but it is
still not a particularly effective solution. The University of Florida Extension concurs that this practice is less harmful
to x Cupressocyparis leylandii than it is to other species, but they still do
not recommend it.

Peter McHoy’s A Practical Guide to Pruning (New York: Abbeville Press
Publishers, 1993)also advises avoiding topping, but also notes that if one must top
an x Cupressocyparis leylandii, it should be done in midsummer and repeated
every few years.

However, in general, it would appear that topping is very much a last resort.

One book, Practical Tree Management: An Arborist’s Handbook, by T. Lawrence, P.
Norquay, and K. Liffman (Melbourne: Inkata Press, 1993),
recommends that “Where a tree requires severe reduction or radical alteration
of its aesthetically pleasing, natural growth habit, it is usually far better to
consider replacing the tree with a species more suitable for the situation…”
Thus, you may consider an initial pruning and eventual replacement.