I replanted my plants last winter as I realized they were too low in the soil, looked terrible, and I pruned extensively. We had, as you know, torrential rains this past winter. Plants are in semi shade not getting any sun in the afternoons. Plants look so, so healthy but there are no buds at all. ????? Each plant is now about 2-3 feet high.Thank you so much for your answer.
The oak leaved hydrangea (Hydrangea quercifolia) is a mound forming, deciduous shrub bearing heads of white flowers that fade to pink, from mid-summer to autumn. The deeply lobed leaves turn bronze purple in autumn. This all makes for a very attractive plant. It prefers well-drained but moist moderately fertile soil. It grows well in partial shade and tolerates some sun. This plant prefers a neutral to acid soil and should be in a sheltered spot. There should be no problem meeting these conditions in the San Francisco Bay Area.
It is advisable to keep pruning to a minimum, so on that front you may have overdone it. New blooms come from buds formed on old wood. If you pruned out a lot of the plant last winter there is a strong chance you will have to forego blooms this season and wait for the next. Your plant is healthy so that is good. A fertilizer with a high phosphorus count will improve future flower production.
Attached are some links to previous responses that Toronto Master Gardeners have answered on Oakleaf hydrangea, which hopefully will be of help to you.