Purchased this tree, japanese maple – dissectum Garnet, two/three months ago and repotted it some weeks later into a larger deeper pot (see photos) in John Innes 3 and also put gravel in the base for drainage. As you will see from the attached photo, it is situated in a sheltered location which gets plenty of morning sun which, I understood to be the ideal for this species! Unfortunately, the foliage is showing signs of withering. What could be the reason?