How to Prune a Thuja Arborvitae

Thuja arborvitae is popular for its fast growth, but that very trait means you will need to prune it regularly if you want to maintain a particular size or shape--especially if you are growing it as a shaped hedge or decorative plant. Because arborvitae is such as fast-growing plant, when you prune is not as important as regular pruning and making sure that new growth does not get out of hand.

Difficulty: Moderately Easy

Instructions

Things You'll Need:

• Sharp pruning shears
• Bleach

1. Wait until late spring or early summer after new growth for the season is well under way before pruning the thuja arborvitae because, ideally, you should limit pruning to new growth.

2. Clean pruning shears by spraying or rinsing them with a mixture of bleach and water, about one part bleach for every nine parts of water. Cleaning the shears will help prevent the spread of disease among plants.

3. Prune new growth that is outside of the desired shape and size of the plant. You do not have to cut a certain point on the branch, but you should make a clean cut. Avoid cutting old growth if possible, because it may not grow back and could leave a bare spot on the plant.

4. Repeat the pruning at the end of August or as temperatures begin to cool slightly. Remove only the branches and new growth necessary to maintain the desired shape and size of the plant.

5. Trim stray branches and growth between prunings to keep the plant neat.

Tips & Warnings

• Set a schedule for pruning and stick to it. Thuja arborvitae is easier to maintain if pruned regularly.
• Don't use dull or dirty shears to prune your arborvitae. Dirty shears or ragged cuts can introduce disease.

References

• Bachmans