Four bushes eight feet tall can I shorten them down to four ft gardenias
Been seven years since I cut back further than a foot.
Certified GKH Gardening Expert
You can do some aggressive pruning, but it will require doing it at the right time. I would also do this over a week's time, so as not to shock the shrub. This article will help: https://www.gardeningknowhow.com/ornamental/flowers/gardenia/when-to-prune-a-gardenia.htm