Pink to Blue On the still rather obscure reasons why
a pink flower, especially the hydrangea, often becomes blue, or vice versa, I am informed that the causes were reviewed in the R.H.S. lournal ten years ago. The learned author poured scorn on the idea that iron in the soil could affect the colour, though the belief is almost universal. His own theory, based on the analysis of the ash of blue and pink flowers, was that aluminium was the agent. "Aluminium is taken'up as long as soil acidity is maintained, and as none is lost by transpiration there is an increasing concentration until the leaves fall so that a plant may open its season with pink flowers and end with blue." It might well be worth while for the research workers, say at Rothamsted, to investigate this odd occurrence and deliver a final verdict. It often happens that important discoveries arise from enquiry into such small phenomena. At the worst, hosts of gardeners would be interested.
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