You may have to set up some sort of watering system, either a soaker hose or drip waterer, or plant in pots that will keep the water where you want it - with the ornamental plants, not the treee roots. What kind of trees are they - some trees are better than others abouit sharing their space with ornamental plantings?

In any case, you can improve matters greatly, whatever you do, if you mulch at a rate of at least 4 inches - no more than 6, and maybe only 5 - around the trees and the plantings. If you do have grass growing under the trees, then there's hope for growing other things, but if no grass, then only the toughest things, or the pots, would be possible, as the tree roots will take up every drop of available moisture. Mulching will help keep whatever moisture there is, in the soil, but if you pile it too deep, you encourage the tree roots to grow up and into it, NOT what you want!!

You can try such natives, and their cultivars, as Virginia spiderwort (Tradescantia virginiana and hybrids), green-and-gold (Chrysogonum virginianim var. australe), downy skullcap (Scutellaria incana), thimbleweed (Anemone virginia), Texas bluestar (Amsonia ciliata), butterflyweed (Asclepias tuberosa), downy phlox (Phlox pilosa), threadleaf coreopsis (Coreopsis verticillata), brown-eyed Susan (Rudbeckia triloba), aromatic aster (Aster oblongifolia), wild ageratum (Eupatorium coelestinum - be warned, it spreads rampantly in good garden conditions), false dragonhead (Physostegia virginiana), various goldenrods (Solidago spp.). These, with initial watering for the first few months to get them established, evolved to grow under dry woodland conditions, so should be able to adapt to your yard. Some might want sandier soil, but you could amend the planting area for them, if you wanted to go to the effort.

The small shrubs you could plant include American beautyberry (Callicarpa americana), oakleaf hydrangea (Hydrangea quercifolia), fothergilla (Fothergill major), yucca, (Yucca aloifolia), Georgia basil (Calamintha georgiana), golden St. John's wort (Hypericum frondosum), or maple leaf viburnum (Viburnum acerofolium). Again, all of these are native, woodland growers, who can tolerate dryness. All flower, and some have fall color or berries.

Good luck.

I'd add celadine poppies, hellebores, spigelia, pulmonaria, phlox divaricata, columbines, hardy cyclamen, and toad lilies. Some violets would do well there and you may be surprised at how well some daylilies bloom in shade. Variegated foliage with whites and golds help lighten up shady areas too and provide interest all season. For dry shade variegated solomons' seal does wonderful and hostas will do alright if the trees aren't real water hogs. Also if the trees are deciduous some early blooming bulbs such as daffodils and crocuses might do well there. Good luck! -Ais.

Thank you for the suggestions! You've given me some great ideas.

Ginger

Heauchera and Tiarella thrive under my trees, with no extra water after first season. Also on this short list: purple coneflower, beautyberry, viburnums, white woodland phlox, hellebores, calycanthus, northern sea oats, variegated dogwoods, Blue Curls, prone cotoneaster, epimedium, camellia, foxglove, columbine (canadensis), clethra. These plants, have not only lived, but spread in my teribble dry shady clay, with minimum amendment around rootball when planted. Purple coneflower seeds itself around and turns up in odd sppots, blooming, until the deer find it.

My trees are oaks and my soil is sandy loam - so it stays pretty dry unless it rains over an inch and even then it dries out completely in a day.

There is no sunlight at all until all the leaves fall off the trees (which is always a little later in the fall than in other peoples yards).

Plenty of plants will survive but few will thrive and form large masses of plants, which is the look I am aiming for. I have most of what has been suggested above. Two plants that have performed really well for me are Rhodea and Carex. The Rhodea have done better if planted in a large pot sunk into the ground. The carex does the same either planted directly or in a sunken pot. The variegated carex species have done so well that I can divide them each winter and expand them into the furthest darkest corners. There are so many carex species available that there is bound to be one that has the look you are wishing for. Rhodeas can be pretty expensive for the fancy leaved forms but the normal dark green ones are my favorite and the cheapest.

Learn to love moss.