Every gardener/designer has their own ideas on groundcovers. I thought I would share what I do with my hydrangea.
At the base of the shrubs, and forming a nice ‘sweep’, I plant the small tubers of Arum italicum ‘Pictum’. This delightful little plant is the ideal workhorse groundcover for any shrub that looses its leaves in winter. It does not appear till October/November, the handsome foliage persists all winter, and disappears in mid spring, just as the shrubs leaf out.

Here the Arum covers what would be bare earth as the Annabelle hydrangea (Hydrangea arborescens ‘Annabelle’) is cut back early spring. (See the stems peeking out?)
Weeks later, the Annabelle starts to fill in. By the time the Arum foliage dies back the hydrangea will shade the ground.
PLEASE NOTE: do not prune all your hydrangeas. The macrophylla type hydrangeas (big blue or pink mophead or lacecap flowers) formed their flower buds last year. If you prune them, there will be no blooms this year.

ANTICIPATION!
The flower buds on Hydrangea macrophylla .