I grow lots of hydrangeas of different colours, and all of them live in pots. I water them only with rainwater because I have heard that they dislike it from the tap. However, I have emptied my water butts due to the dry weather. Is there anything I can add to tap water to make it more acceptable to them?
Rainwater is definitely the best choice for your plants in pots. It’s good for the environment to be collecting rainwater like this and it’s also the most suitable for acidloving plants which don’t like the hardness of tap water. However, as a temporary measure it’s fine to use tap water. Your blue hydrangeas may turn pink over an extended period as they lose their ability to absorb aluminium from the soil, but once you resume rainwater, things should return to normal.