How to change the colour of hydrangeas?
“The acidity of your soil will affect the colour of blue, pink and mauve hydrangeas. Acid soil will give blue flowers, neutral to alkaline soil will give pink flowers. If your hydrangea is white it will always be white regardless of the soil. The blue colour comes from hydrangeas which take up aluminium. So the secret to making your hydrangeas blue on soil which is not naturally acid is to add aluminium sulphate to the soil. Don’t do this every year though, it can cause problems. Alternate aluminium sulfate one year with sequesterd iron the next. There are lots of hydrangea colourants on the market. Be aware though, to get the bluest booms you really need naturally acid soil, the pH should be between 4.5 to 5.0.” http://www.gardenaction.co.uk/plantfinde… See also: http://www.hydrangeashydrangeas.com/colo…
