What can I do to revive them? I think they're dying. They used to do pretty well but seem to have gotten this way over the past couple of years. Could it be the soil? We spread mulch or compost at the beginning of each season.
My Impatiens Are Leggy and Shrivelling Up
Certified GKH Gardening Expert
If they are leggy, this indicates that there is now too little light. And the fact that you say that it seems they have slowly gotten more like that supports this. It sounds like the shade over the plants (which I am guessing is from trees) has gotten heavier. This is normal for trees. As they age, their canopies get more dense.
You can look to see if there is some pruning you can do to least a little more light through. It would likely do the trees some good as well. Remove crossing and rubbing branches, branches that seem weak or diseases and branches that could damage building by rubbing or thrashing in a storm. Typically, if you remove these kinds of branches that are problems for the tree anyway, you can let enough light in again to have a good shade garden area.