Encouraging growth on bare branches of white cedars

(Question)

Is there any way to encourage foliage growth on sections of white cedar branches or trunk that are bare? I have a 25ft hedge in the Toronto area. The soil is heavy clay, the hedge is in Sun in the summer. The hedge was cut back heavily 4 years ago. Some sections/trees show all kinds of new growth on what were essentially bare branches and section of trunk. However, other trees have remained completely void of growth. Is there any way to initiate growth on bare sections of trunk or branch?

(Answer)

After four years, the trees will revert to what they would do naturally. The tree will continue to grow densely at the top, reaching for the sun, and sparsely at the side.  If you have ever been in a cedar forest, where the trees are packed closely together, that is exactly what happens. The branching dies off lower down on the tree, but continues to grow vigorously at the top.

The key to keeping cedar hedges dense from top to bottom,  is yearly pruning; usually pruning at the top to match the shortest tree in the hedge, and a light pruning along the sides in early spring, before growth begins, encourages new growth. Do not prune past July, to allow new growth to harden off for the winter. As well, fertilizer with high nitrogen and iron to encourage growth.  Cedars benefit from mulching, and since yours are situated  in clay and get full sun, keeping moisture around the roots can only benefit the hedge. Mulch to a depth of about 3 or 4 inches (7 to 10 cm).

The Toronto Master Gardeners have a fact sheet “EVERGREENS SUITABLE FOR HEDGING” which advises trimming a cedar hedge in June.

For further information:

http://mark-cullen.blogspot.ca/2010/09/cedar-hedges-investment-that-grows