- Botanical Garden
It is preferable to prune thuja (or cedar) hedges towards the end of June, when the trees have completed most of their annual growth. Generally, between one and two thirds of the new growth is pruned. It is possible to prune at the end of the summer, but it is difficult at that time to tell how far you can go without touching old wood, because new growth will have lost its distinctive colour. Healing is also quicker in early summer than in the fall.