This issue comes up over and over! You will find you are not alone. Check threads on the perennials forum too, you will find lots of great suggestions. Do a search with some keywords. I have the same conditions, under 3 ash trees. The things to remember are, you need perennials that do not mind tree roots for competition. The trees will suck out much of the water so you probably have dry shade. There are lots of plants that like moist shade but fewer choices for dry. The bulbs DO like it dry so that part is good. I find that the bulbs in my tree area perform well year after year, much better than in my main garden.

FWIW, you can have the benefit of what IÂve tried. I also have astilbe. They have grown incredibly slowly. I like them but will not buy more for there unless I can get them really inexpensively. Hosta donÂt like it there. They live but donÂt grow. After 5 years some are the same size as when I planted them. Lamium is doing well. Hardy true geraniums (not the annual pot "geranium", which is a different species) like geranium sanguineum seem to be doing well: not much bloom there but they have attractively shaped leaves that also turn color in the fall so it doesnÂt matter. Ferns are doing well. I am trying the woodland route with some trilliums. But the hardy geraniums have been the best. There are many colors available.

How about Forget-me-nots? They do well in part shade. They are called Myosotis Copindi (Forget-me-nots). Or campanula's, heuchera's?