What can be the blueest mophead Hydrangea?

I'm looking for the perfect (blue!) S. California hydrangea, really, but I'm mostly looking for a stronger blue as my soil doesn't seem to have much aluminum or my regular fertilizer is binding it out somehow.



Right now I'm growing: 'Ami Paquier', which never goes past lavender; 'Dooley' and 'Penny Mac', both of which will go pale blue ('Penny Mac' blooms are willing to switch mid-growth, making odd color mixes); and H. m. nigra which will daintily picotee sharply blue.



'Penny Mac' never stops blooming except in February, but doesn't keep color so I am constantly having to prune old heads off. 'Dooley' doesn't seem to like my lack of humidity, and is growing very small. H. m. nigra has beautiful black stems and takes walkway abuse well, but is highly succeptible to powdery mildew. 'Ami Paquier' blooms very early, keeps color, and is mildew-proof.



Anyone have dry-hot weather experience with 'Endless Summer' or 'Enziadom'? Are they good blues here?

What can be the blueest mophead Hydrangea?
I'm in Ohio %26amp; yes the Endless Summer can be a very deep blue if the soil is acid enough. Add Holytone %26amp;/or Aluminum Sulfate help to acidify soil.

I don't think our hot %26amp; dry is anything like your hot %26amp; dry, so I don't know how it would perform for you.