Watering Dog Wood Trees?

I bought some weeping cherry trees and a dog wood trees from a different area last spring online. I lost some of them as they were very small saplings. The ones that are living now are in my veranda and get limited sunlight. I have an automatic watering system. Both the dog wood and the weeping cherry trees have a lot of leaves but they are turning brown at the ends. Am I watering too much or still too little? Please help. I can send photos if you need them.