Looking for some advice. I purchased a 6' - 7Ã¢â‚¬â„¢ Japanese Maple late last summer and due to landscaping delays it didn't get planted. It stayed in the greenhouse at the nursery I purchased it from over the winter. When I picked-up the tree ten days ago it was fully leafed and I transported it in the back of a pick-up with the head fully tarped. The tree sat in the planted container in full sun throughout the morning and late afternoon until two days ago when I planted it in the same area using a four mix topsoil. During the last ten days we didn't get any frost but had some nights that dropped to 5-7 degrees. About 5 days ago I noticed some browning on the leaves and it's gotten progressively worse with nearly all of the leaves having some brown on them. The tree is also seeding, as you'll see in the attached photos. The browning of the leaves seems to be a precursor to the leaves drying and falling off.
The nursery indicated that I didn't have anything to worry about unless there was a frost and we didn't have any frost since the tree arrived. Was it just too cool on some of the evenings (5-7 degrees) for this Japanese Maple and is this why I'm losing leaves? What can I do to help the tree?
Thanks for any help.