Hydrangea Nutrient Problem

It looks like your Hydrangea is having similar problems as your Camellia – possibly leaf tip burn, but this photo doesn’t look like Nitrogen deficiency. Both of these plants are acid-loving, and as we mentioned in reply to your Camellia photo, water (and soils) in So Cal are alkaline. This could cause nutrient uptake issues (not enough of certain nutrients, and/or too much of others, causing a toxicity, or tip burn). We’ve included two more links, one for Hydrangea and one for Camellias that will provide good information about growing these plants, and some of the issues they can have in So Cal landscapes.
http://www.ipm.ucdavis.edu/PMG/GARDEN/PLANTS/hydrangea.html
http://www.ipm.ucdavis.edu/PMG/GARDEN/PLANTS/camellia.html