I also live in NW Washington state and have three hydrangea's planted. the one that does the best is the one on the western side of the house, planted up against the wall. it is somewhat sheltered from the wind, gets a lot of sun, and very little water, It blooms a lot. the second best one is against a fence with western sun, but it gets shade about half the day and more water. the least effective one is close to the leland cypress and in the shade alot.