I recently bought a house in Victoria that has a photinia hedge all along the side of the house, that was probably never trimmed, and is now about 15 -20 feet high. The stems are all bare up to about 5-6 feet and the trunks are between 3-6 inches in diameter. We hard pruned half the hedge last year as an experiment down to 6 feet tall. No leaves were visible when we were finished but it sprouted leaves and branches near the top that are now about 1 foot long. We want to cut the whole thing down to a foot tall and let it rejunvenate so we can trim it back to a hedge over time. My question for you is whether this is too much to expect as we would have to cut through some 6 inch stumps. Will anything grow back from such a big stump? Also can we cut the half of the hedge we didn't touch last year right back in one go? Or will that be too much for it? Your thoughts will be appreciated.
The thinness is probably due to leaf spot, which is spoiling this shrub for use in North America. Already weakened by the existing partial defoliation, hard-pruned specimens deteriorate further. If your hedge is gaunt with spotty or blotchy leaves, it has leaf spot and will need to be replaced with another selection - if you are not going to be spraying it for leaf spot every year, in perpetuity.
