Hydrangea (Hydrangea macrophylla)

Boasting magnificent blooms, hydrangeas are associated with many cultures, with each having its own interpretation of what the flower symbolises – from heartfelt emotions to heartlessness, as well as abundance and prosperity.

Native to Japan, hydrangeas have since been introduced to many parts of the world such as New Zealand, parts of Southeast Asia and Central and South America. In addition to being a common landscaping option or part of houseplant collections, it serves as a popular cut flower choice for centrepieces or bouquets.

The large mophead flowers of hydrangeas are made up of individual blooms that are relatively inconspicuous but enhanced by a ring of bracts (or modified leaves) around each flower. The striking colours of hydrangeas are from these modified leaves, designed to attract pollinators. A familiar example of modified leaves can also be observed in bougainvillea.

Hydrangeas can also change from pink to blue and vice versa! The colours can be controlled by manipulating the pH levels in the soil – by adding lime to raise the pH level to achieve pink blooms or sulphur to lower the pH level for blue ones!

Botanical Name

Hydrangea macrophylla

Common Name(s)

hydrangea, big leaf hydrangea

Plant Type


Mature Size

Up to 2 m in height


Does well with morning sun. Adaptable to minimal light conditions indoors.

Water Daily watering

Well-drained soil


Inconspicuous flowers surrounded by brightly-coloured bracts


All parts of the plant contain cyanogenic glycoside and are poisonous when ingested. Poisonous to cats and dogs.

Written by: Agatha Koh, Manager (Education, Programming & Events)

Agatha has spent the last ten years in a green paradise of every kind – greenhouses, orchards, food forests, therapeutic gardens, nature parks. Her days at the Gardens continue to be happily plant-filled as she shares her love for plants with fellow green thumbs and floral fanatics!

This article is part of our Bringing the Gardens Home series.