My wonderful neighbour very generoulsy gave me a massive hydrangea BUT je n’aime pas le couleur rose. Wikied how to make it blue - peeps rabbit on about ph and sulphur - where doe one get sulphur? I’ve tried the rusty nail ruse to no avail. Merci les tous comme d’habitude.
Any garden centre. Bear in mind though that the effect may be “muddy” rather than true blue if your soil very much favours pink.
For some reason Eopsom Salts springs to mind, when talking about hydrangeas… and wanting blue flowers…
And collect your coffee grounds and keep spreading them around the bush will help keep it blue. Plus eggshells - I collect them in a container and when I have a enough I blitz them in the blender to make a gritty addition around plants.