Thuja occidentalis "pyramidalis" is an evergreen shrub that can grow up to 30 feet high and 10 feet wide. It prefers Zones 2 to 7 and does best in full sun and well-drained, normal to moist soil. However, the species can handle heat, drought and poor soils. Thuja pyramidalis' soft, kelly green foliage can be trimmed, pinched, sheared and rejuvenated. Pruning thuja pyramidalis improves the shape, allows you to control the size and increases the circulation of sunlight and air inside the tree.
Pinch off the stem tips of new branches. This promotes more growth inside the thuja pyramidalis and fills in gaps to make the shrub bushier.
Use pruning shears to cut overcrowded branches back to the trunk. Make the cut where the unwanted branch meets other wood. This will open up the tree's canopy to allow more air and light circulation.
Remove diseased, dead or weak branches by cutting them off at the V-shaped connection they share with healthy wood. Make the cut on the healthy wood.
Shear off the sides and top of the thuja pyramidalis to shape the shrub. Run hedge clippers along the branches, removing the bulk little by little until the desired form emerges.
Remove old wood on the inside and outside of the shrub to rejuvenate the thuja pyramidalis. Make sure to choose branches wisely, so you don't create gaps. Cut off the old wood at the collar, which is the thicker section of bark at the base of the branch. The wound will heal fastest here.