Paco - 6 months ago
Hot weather is rough on Japanese Maples, try to keep them shaded and misted if possible. I can only share what has worked for me, moisture level I find is very important as dry air will cause leaf damage. Ideally a green house would work great, if you don't have a green house, a shady area that gets mist works. If your trees are planted and are well established, a deep watering should help, but if it's recently planted you may need to provide temporary shade with some sort of shade structure.