How can I get my golden seal plants to grow ?

I can barely get my golden seal plants to make it through the summer. Is there something I can do for them to make them get bigger and shoot out more rhizomes ? I water them almost every day when it's hot and they have a lot of shade. I live in southern Missouri (USA). I'm sure the hot summers are hard on them but I really want to get them to grow. Their leaves shoot up in the spring nice and green but then they start turning yellow and looking sad and they never have red berries in august like they should. They look like they're barely alive in the fall when they go dormant. I've been trying for a couple years and can't get them to do any better.