Answer: It's true - most Japanese maples do best with morning sun and shade from the hot afternoon sunshine. With too much intense sun, the foliage tends to fade and can sometimes turn crispy around the edges. Partial sun means a few hours of morning sun and at least some filtered shade in the afternoon.
As for your two new trees, the top growth is new and has not had a chance to harden off. Leave the birch alone; the top will become more rigid as the growth matures. The stress related problems with your zelkova will improve as the the roots become more established in your garden. I would simply watered them well each week and allow them to adjust. Watering every other day is excessive, even in the hot summer months. It is better to water deeply once every 7 days to promote deep root growth. As the weather cools you'll only need to water once a week. I think one of the best ways to provide a deep soaking to trees and shrubs is to make a watering well or watering basin beneath each by mounding up a few inches of soil in a circle, about 12" from the trunk. Fill the basin with water, allow to drain, then fill a second time. Watering once each week in this manner will concentrate the moisture over the root mass, and allow it to trickle down, wetting the entire root system.
Best wishes with your garden!
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