How to make my hydrangea flowers turn blue?

I moved to a new house and there are older hydrangeas in the front yard. They are just now starting to bloom and Id like for the flowers to be blue. What do I use? And how often?

How to make my hydrangea flowers turn blue?
there is an acid based product on the market that you water the plants with to make the soil more acidic which will change the color of your hydrangeas
Reply:Depending upon the hydrangea, if it is a re-blooming hydrangea such as endless summer - picture here http://www.naturehills.com/product/endle... and the blooms are pink you can put down aluminum sulfate in the soil to change the blooms to blue. Unfortunately the bloom on the plant now will remain pink but new buds turning to blooms will be blue. Be careful to follow the packages instructions. I have 7 hydrangeas and just yesterday I put down some aluminum sulfate.
Reply:nothing you can do for this year.... if the flowers show up to be pink, you can start to change the soil pH with aluminum sulphate over the next year or two and it might work....





read here for complete directions...





http://www.hydrangeashydrangeas.com/





on the left side down a ways.......color change.....
Reply:The old gardeners used to plant rusty nails near the pants roots. This puts the nutrients into the ground to make the flowers turn blue. You can try it and see if it makes a difference, what have you got to lose?
Reply:Here is a good website all about hydrangea:


http://www.usna.usda.gov/Gardens/faqs/hy...
Reply:Acidify the soil.........in years past we used aluminum sulfate fertilizer.





Are you sure they are the right hydrangeas?
Reply:You can buy a special formula at your garden store to do this, I think if you ask they will advise you.
Reply:Aluminum sulfate and use miracid
Reply:my dad put like rusty nails and stuff in the bottom of the soil and that seems to work for him :)