True geraniums—which make fluffy little mounds of foliage and small flowers in white or shades of pink or blue—thrive in the
light shade of high trees.
At Sunset headquarters, we grow G. x cantabrigiense ‘Biokovo’, which has white blooms with a pale pink blush in late spring and early summer, in a bed under a shapely oak (it doesn’t need much water).
Other pretty choices include G. cinereum ‘Ballerina’ (pink flowers), ‘Brookside’ (blue flowers), and ‘Jolly Bee’ (blue flowers).
More: Geraniums in the Sunset Plant Finder