[header] How to prune arborvitae [title] Shear in early spring. [step] Early spring is a good time for heavy pruning because new growth hasn't started yet. When new growth does come in, it will hide the cuts you made in the tree. 
[substeps] To shear the plant, go over the whole plant with your pruning shears. Trim the tips off all of the branches to create a more even shape.