Manipulating the Ph factor when they are small is easy & fun. But as they mature into larger shrubs, it's not so easy. 6.5Ph=blue hydrangea. They root very easily though, so you can try taking a stem cutting & keep it in an alkaline environment.

Are the flowers cone shaped or rounded?

Its a mophead Bamboo. I can't understand why liming it didn't make any difference. Maybe I should have used more? No way am I going to start again now its four feet high and more across! Just been out to look and its rapidly turning into a rich deep blue but its taken 13 years. Perhaps working in some limestone chippings?

When did you lime it? You must be consistent with the lime and you won't see results for a couple years. The substrate Ph usually prevails. You are better off putting your hydrangea is a separate tub where you can have more control.

Yea, when did you lime it? needs to be done early in the year, February say, to have much effect on the flowers the same year.

I limed it a couple of years ago and am pretty sure it wasn't February but can't recall just when. It seemed to me that there was a very small change in flower colour but it was another tendency towards blue and probably had nothing to do with the lime. How much lime should I add next winter? I didn't add a lot to start with, just wondering if it would work. Some years ago I gave it a mulch of fresh (washed) seaweed - do you suppose that would have made any difference (apart from an impressive growth spurt)?

Bathgate it is far too big to move to a tub. I know that would work, as a friend who had a cutting from it has kept hers in a container and its a lovely red, but its growth potential is severely limited by the container size and I would like mine to grow large to balance the blue one and the Annabelle in the same bed.

Whilst there are tables for working out how much lime to add to larger areas, I can't find anything regarding using restricted amounts for a single plant in a bed, so its guesswork I'm afraid - maybe a couple of handfuls? And the seaweed might have caused extra acidification of the soil if it was a variety high in sulphur.

Stera. I have the opposite problem: I want my pink hydrangea to be blue. Check out 'Strawberries & Cream' hydrangea. It's a looker. If you like this, place an order. This one is Strawberry pink and white.

Could have been the seaweed then - it did wonders for the health and growth rate anyway.

I do like that one Bathgate but it doesn't solve my problem! I haven't got a suitable place for any more, I've already squeezed in five...
Basically by now I want to know what to do more than I want the result - silly isn't it? I'll wait until winter and sling on some more lime.

Try aluminium sulphate for your pink one, and/or sink a few rusty iron nails round it, which I've read works.