Have you considered ferns local to your area. Most can take quite a bit of shade, very hardy, and many will slowly spread and colonize. Started with one species but it became a bit of an addiction. Also have Pachysandra, Coral Bells, Irish moss, and Vinca vines in deep shade--they're also everygreen, as are a few of the fern species--at least locally. Good luck!

The reason plants do not grow well under the canopies of large trees is due more to dry soil conditions rather than to heavy or full shade, The trees just have larger and much more aggressive root systems than do the much smaller perennials or groundcovers and they hog all the soil moisture and nutrients.

Look for plants that are recommended for dry shade: Epimediums, bigroot hardy geranium (Geranium macrorrhizum), fern leaf dicentra, Euphorbia robbiae, etc. In the groundcover catagory, look for Lamium maculatum (dead nettle), Galium odoratum (sweet woodruff), winter creeper (Euonymus fortunei), oregon grape or bishop's/goutweed (Aegopodium podograria). English ivy - if not invasive in your area - and vinca will work also. Pachysandra does well in full shade but needs a moisture source to look decent and fill in well. Irish moss is not a moss at all and would appreciate full sun and even moisture much before a dry shade condition.

There is actually a strip of ground along the side of my driveway that is literally under the house--getting very limited sun and water. Vinca was already growing there, I added some mini Dicentra (bleeding heart), Hedera canariensis (Algerian Ivy), and Ajuga. Ended up moving the Ajuga as they didn't excel as much as I expected.--Now they're in a shady but moister location and looking good. I understand the point about soil moisture being lower under trees but my location is wet enough year round for this not to be a concern. I try to keep most of the English ivy in check--as it really can be aggressive as suggested above--climbing into trees and smothering them. Which is why I ripped out most of it and replace it with the Pachysandra. I knew that Irish moss was not really a moss but still it has been thriving in a fairly shaded location under Canadian hemlocks--but then, soil conditions are very moist.

No, under the oak tree it is always moist and when there is a light rain the rain reaches the bottom. The pine tree is the only tree with dry soil underneath it and it has to pour just to reach the soil.

We have a mature maple with very dry soil at the base.

I've planted both Pachysandra and Vinca. While Pachysandra does well under pines, not so much under my maple - I agree with the previous post, it needs more moisture.

Vinca minor, on the other hand, has thrived providing a nice groundcover. It took a few years to establish and spread nicely, but I also didn't do anything as far as adding amendments or special care. I give this one an A+ for dry, shallow soil. In anything else, I believe it's known to be invasive, so keep to a confined space. Not so in its present location. Nice spring flowers too.

Hi - I use oxalis, it has delicate pink blooms,
strawberry begonia, has a tiny white bloom,
liriope spicata/monkey grass , it has pinkish blooms,
ajuga/ bugle weed - it has nice purple blooms,
vinca vine- evergreen here, has a variegated cream with green leaf
and has a lovely blue flower. Just a few of my favs. Good luck - tina_2

Let's not forget lilly of the valley. I have a section in complete shade under an oak tree that does very well.