That is certainly my understanding Myron

I think you can buy 'stuff' at the GC Myron. It's my understanding that you can't change a white one though.

hi if you put old nails at the roots they change the colours aswell but not the galvanised type.old rusty ones etc etc.

Aluminium sulphate to make them blue..

Thanks for naming the 'stuff' P. Was just about to go check out what it was called an update my post....don't need to now :)

Spot on Pimpernel! Sequestered iron also provides an acid base but have found this has more affect on chlorosis of the leaves, whereas A.Sulphate has more effect on the colour of the blooms.

I think acid turns them blue.

Also ... pink/red hydrangea will become more blue on an acid soil, so if you wish them to remain pink/red apply a dressing of ground limestone during the winter.

Note that all the advice above applies only to varieties of Hydrangea macrophylla - the other varieties have flowers which are unaffected by soil ph.

Thanks for all the advice. It's interestesting to find out that "Old Nails" will change the colour. At first I thought you'de gone mad Kenny, thought you'de missed the "S" out in front of the word "Nails", haha. I suppose any rusty iron would do?

I remember my father trying the nails idea didn't really work as well as he would have liked stick to Pimpernel's advice if you want blue hydrangeas.

There are many varieties of hydrangea - some are bred to have pink flowers and some are bred for blue ones. Trying to get a pink one to go blue (by making the soil more acid) doesn't entirely work - they go a sort of muddy pink. Likewise, blue ones in an alkaline soil don't turn a true pink either

Hi Myron, hi Moon grow. Rusty nails or even aluminium sulphate for those more developed (lol) doesn´t work, if you do not correct the pH of the soil before. That means, first add turf to the roots and then aluminium can penetrate to the roots. Otherwise - acid soils make hortensia flowers blue, while alkaline pink or white.Some stay white whatever you do. Lol.