Sweet woodruff, Galium odoratum, would be a good choice. Relatively low growing and will take a lot of abuse. Slightly fragrant white flowers in May. In fact, I'd recommend restricting this plant to a tough growing environment as it can spread very aggressively if planted in better conditions :-) Vinca minor is another possibility and is also evergreen (or very nearly so in your climate).

English ivy is evergreen and quite tough if you choose one of the hardier cultivars. You could actually try growing more than one species and just let them fight it out to dominate the planting area. Sweet Woodruff with either vinca or ivy would be an example.

Hi all, I'm new to gardening and to the forum, and I have a related question.

We live in Philly and have a backyard with poor, dry soil that is shaded by a large weeping willow. The area does get some dappled afternoon sun. We have been trying in vain to find something that will grow there to keep the dirt down. It sounds like Vinca would be a good idea, but are there other plants (aside from hostas), perhaps even flowering ones, that would grow in these conditions?

Thanks in advance!

In my worst, driest shade soil, I have lamiastrum growing. It's varigated, blooms yellow in the spring, and is almost as indestructible as (shudder) Bishop's Weed. Anything you plant will need to be watered it's first year, but after that (at least in this bed), they're on their own.

judeinpa - Geranium macrorrhizum might work if it's hardy in your zone. There are several cultivars with pink, purple or white flowers. Another idea is things which would bloom before the willow is in leaf such as Corydalis solida, miniature daffodils etc. There are also ferns which will cope with dry shade.