We've had quite a few rainy, gray, overcast, thunderstorming days here, but that doesn't stop perennial borders from having the sunny look. Say it with a splash of lemon, lime or gray. The lime green "Angelina sedum" makes it look like the sun is shining brightly. (It is super easy to root any cuttings from all sedums.) All lime green and gold leaf foliage does this trick. Grays even look bright on overcast days like the lamb's ears, stachys byzantina, zones 4-7 here with the sedum. My head is spinning with color and foliage combinations most days rain or shine.