2021 - What I did today

Mostly pink, wishy washy blue hydrangeas round here. If I see an intense blue one I assume they've treated it with summat - is it copper pennies or am I making this up?

EDIT the duckduck told me that the colour depends on the level of aluminium in the soil. Acidic soils allow the aluminium to be released from the soil to the plant.

https://www.gardenmyths.com/hydrangea-myths/

Clever little duckduck! Intersting article that.