Making hydrangea blooms blue

I love hydrangeas.  Yes, they're old-fashioned (which perhaps is a bad thing to some folks) but I find them beautiful.  When we bought our house 4 years ago, there was a large mophead hydrangea bush in front of the house.  It wasn't in great shape, crowded out by overgrown junipers, and it bloomed in pepto-bismol pink.  I don't like pink, and I don't like pink flowers.  But as I said, I love hydrangeas.

So I got rid of the nasty junipers and added 5 more "Endless Summer" hydrangeas.  These are mopheads that flower blue in acidic soil and pink in alkaline soil.  All that pink made it clear what I was dealing with.

I tried to be patient about this, adding pine needles as mulch and a bit of aluminum sulfate a couple times each year.  I don't like going crazy with chemical amendments.  And now, my patience has paid off.  Approximately ten percent of the blooms are purplish, but the rest are blue.  Yay!