Welcome to ATP, Vicki! Not too many Kansans on here yet...so we need to help one another!
In most places in Kansas, hydrangeas must be supplemented yearly with an acidic compost. Plants around the hydrangea should be able to tolerate acidic soil. I have to plant hydrangeas and azaleas in 1/2 peat moss and 1/2 compost! The heat and wind depletes the soil moisture so quickly here!
I like to plant white begonias around the hydrangeas--the kind that come in a 6 pack. White or pale blue pansies look good there early in the spring before the shrubs really leaf out.
Hypericum, hostas, and nandina do well in the same shady conditions. Solomon seal are very happy there. At first, I was concerned there might be some root competition, but they seem to share space without issues. i have a few clematis and passiflora that climb through hydrangeas. Impatiens always do well also. Japanese iris do ok if there is enough sun--I have mine on the east side of my brick house with full sun through 1 pm and that is enough for the iris and almost too much for the hydrangea.
i hope that helps!
