I have just finished planting lots of canna plants on my
rocky hill, also at the top i put creeping phlox..i think
it will be beautiful next year, you might like to try this, cannas will grow anywhere and since its on a rocky hill, these cannas will keep the land from washing when you dig..patticake

Portulaca is an excellent ground cover for sunny areas and because its a succulent it can withstand drought situation which will apply since it will have to compete with the Maple tree roots for moisture. Also called Moss Rose it gets nice flowers on it throughout the summer and grows 2 inches tall.