The weeping blue atlas cedar is an unusual evergreen whose drooping branches and waterfall appearance make it an excellent accent tree. It is hardy in zones six through nine. Like other evergreens, weeping blue atlas cedars require pruning to remove diseased or damaged branches, to head back new growth and to maintain size (width) and shape. You must stake a weeping blue atlas cedar and train it to grow in the direction you choose; otherwise, it will just trail on the ground.
Prune away any damaged or diseased branch or branches immediately. This should be done when the damage occurs. You can do this at any time during the year---the tree does not have to be in its dormant state.
Use your hand-pruning shears to cut back new growth. This should be done if the plant is spreading beyond its boundaries within your landscape design or if it is interfering with other plantings. You can cut at the point of the new growth. You may also decide to shorten the streamers. The weeping blue atlas cedar's branches have smaller branches that droop and stream out from the main branches. This can be done in early spring after the appearance of the new growth.
Visually assess the tree to determine if you must do any radical pruning and or staking/re-staking of the tree to create the shape and appearance you desire.
Cut away the desired branches. Any radical pruning should be done in the winter when the tree is in its dormant state. You should not remove more than one-third of the tree.