Hydrangeas

I captured these beautiful hydrangeas at the ‘Blue Beauties 2026’ display in the Flower Dome recently. From the display, I was able to glean the following information on Hydrangeas.

What most people call a hydrangea ‘flower’ is not a single flower but an inflorescence, or a compound cluster of dozens to hundreds of florets. The large, showy, papery structures are sterile florets, containing no pollen or nectar and serving to attract pollinators. The smaller, star-like fertile florets bear stamens and pistils, producing pollen and nectar and setting seed. The proportion of sterile to fertile florets determines the inflorescence’s overall form.

An interesting fun fact about Hydrangeas which you may not be aware of. Hydrangeas are by default pink or red. In acidic soils, aluminium becomes available to the plant and alters the flower’s anthocyanin pigments from pink to blue, making hydrangea one of the few ornamental plants whose colour responds to its environment.

In acidic soils, aluminium becomes water-soluble and is absorbed by the plant’s roots. It travels to the sepals where it binds with the pigment and alters its light absorption from the red end of the spectrum to the blue.

Without enough aluminium, even acidic soil will produce pink flowers. This is why commercially sold hydrangeas grown blue with added aluminium sulphate in nurseries might turn pink after planting, if the garden soil lacks enough aluminium to sustain the blue complex.

Hydrangea macrophylla cultivar, commonly known as a "Sumida Fireworks" hydrangea.

This is the Panicle Hydrangea (Hydrangea paniculata), recognizable by its elongated, conical flower clusters.

Hydrangea macrophylla – these are the more common hydrangeas

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