Answer: Sounds like a good project for this spring! It definitely sounds like a droughty spot. There are plenty of plants that withstand drought, and prairie grasses and wildflowers are among them.
First things, first, though: have the soil tested for nutrient and pH levels, and correct them as recommended in the test results. Your cooperative extension service (ph# 309-837-3939) can supply you with testing materials. If the soil is as sandy and well-drained as you say, I highly suggest adding several inches of such as compost, rotted manure, etc. to the top 6" of soil prior to planting, and then cover the area with organic mulch (bark chips, straw, hay, etc.). This will improve the structure and moisture holding capacity of the soil.
Boxwoods aren't on the list of drought-tolerant shrubs but here are some ideas for you: barberry, cotoneasters, junipers, bayberry, potentilla, sumac, currants, rugosa roses, snowberry and beautybush.
Perennials: Blackeyed Susan (Rudbeckia), Yarrow (Achillea), Artemesia, Russian sage (Perovskia), pinks (Dianthus), thrift (Armeria), lamb's ear (Stachys), rose verbena (Verbena canadensis), Marguerite (Anthemis), and lavender. Prairie flowers: Asclepias, Asters, Coneflowers, Liatris. Definitely include some prairie or ornamental grasses in the mix, too.
Even though these plants are drought tolerant, they still need moisture during their "infancy" in order to survive and become hardy. You can "wean" them of supplemental water as they gain strength. This is especially true of the shrubs, which need a well developed root mass to carry them through the winter. Drip or leaky-pipe irrigation on a timer is an easy way to provide moisture while the gardens are getting their feet under them.
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