Brown arborvitae can be saved from conditions that cause it to brown, but it may not be as healthy as it was. But that does not mean it cannot be saved. A branch that has turned brown can grow out and parts of the branch closest to the trunk will grow to their natural green.
How do you save Brown arborvitae trees?
We found that adding new mulch around the base of browning arborvitae will slow down the dying process and might save your tree altogether. Another way to save browning arborvitae is to prune your tree once it begins to show new growth in the springtime.
How do you revive arborvitae?
In extreme cases, weak and spindly arborvitae may be stimulated to fill out by cutting back. Cut the top 2 feet or so of the arborvitae off. Use a pruning saw to make the cut above the nearest lateral branch. The arborvitae will bounce back to produce fuller growth over the season.