Hydrangeas are wonderful, hardy shrubs that would certainly have to be included on a list of the ten best flowering plants in the world. Some people remember the old style hydrangeas that were too tall and lanky. In recent years plant breeders have developed some excellent new varieties which are more compact and come in a range of sizes, which flower profusely.
Hydrangeas are amazingly versatile in that you can actually alter the flower colours to suit your needs. The flower colour in most forms relates to the acidity or alkalinity of the soil. In acid soil (pH 5 or less) hydrangeas are usually always blue. As the soil pH climbs towards the neutral and alkaline end of the scale (pH 7 or more) hydrangeas turn mauve, pink and red. A blueing tonic (containing aluminium and iron) will turn pink or mauve hydrangeas blue. It should be applied once a month in March and April and again in August, September and October, following the directions on the pack. A cup of lime (calcium carbonate) added to the soil in spring will cause blue or mauve hydrangeas to turn pink. White flowering hydrangeas will remain white regardless of soil pH.
This post is part of the Blue Monday meme.