Answer: Unfortunately this type of pruning needs to be done often and very regularly and in just small amounts at a time to maintain the shape. There is no kit that I know of to use. You could try to take it back to the original shape. Use a string and wrap it around the tree in the spiral, then follow that as your trimming guide. Some of the shrubs commonly used for this do not accept heavy pruning very well and may develop bare spots if you have to prune it back hard to regain the spiral. Good luck with your spiral.
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