Can you help with a question about our beloved ornamental Japanese maple?
We have a property in Memphis, TN (clay soil) with a mature Japanese maple that was well established when we bought in 2002. The tree used to have brilliant red leaves but its leaves now turn from red to green when the leaves unfold fully and when spring temperatures get above 80. The greening issue began perhaps seven years ago. We have other Japanese maples nearby (planted later in 2004, a different, more upright variety) that stay deep red all season.
The tree has grown at least 30% since 2002. The property was always shady but has become more so. There are large oaks to the northwest and northeast that have become more dense. One side of the Japanese maple gets direct sun between 8-noon, and the other side is in dense shade. The issue is the same on both the sun side and the shade side.
I don't believe the tree has returned to rootstock - the leaves are red when they first appear. I've gotten conflicting advice from tree services. Some say it's the natural result of aging. Some say it's getting too much sun; some say it's not getting enough sun. Some say fertilize it (which we have, with no result); some say it's getting too much food (so we skipped fertilizing, with no result). Some say it's a watering issue, others say its feeder roots are constrained by a nearby driveway (but this driveway is probably 10 feet from the trunk, and the dripline only overhangs the driveway by perhaps 18 inches).
The attached photos were taken this morning. The leaves are the same on both the sun side and the shade side. The leaves will be fully green within the month, I predict. Do you have any advice for me? Thank you!