A maple needs to be mature to withstand 100 degree heat and frequent watering. Hidden deep root bubblers provide water. The cute blue flowers are on the Ceratostigma are actually 'mulch' in disguise, keeping the roots cool! The smokebush likes very little water. It is downslope from the maple so it recieves some runoff.
Constant pruning will keep the groundcover, maple, and smokebush in balance over the seasons.