Pink hydrangeas turn a ‘beautiful’ blue colour when given 1 kitchen scrap item every month

Many hydrangeas will go through a slight colour change when transplanted due to adjusting to their new soil when you first bring them home. But for those who want to shake things up, try changing the colour of hydrangea flowers with this simple little soil hack.

By Angela Patrone, Lifestyle Reporter

Pink and blue hydrangeas

Pink hydrangeas turn a ‘beautiful’ blue colour when given 1 kitchen scrap item every month (Image: GETTY)

Hydrangea varieties such as hydrangea macrophylla and hydrangea serrata can range in colour from pink to blue, with every shade of fuchsia, plum, and periwinkle in between.

However, the blooms can change colour based on the amount of aluminium the plants absorb from the soil, which depends on the soil pH.

High levels of aluminium in the soil plus an acidic soil pH will generate the coveted bright blue to purple flowers

If there is less aluminium in the soil, it will create a variation of pink blooms

Not all hydrangea species change colour, however. White ones do not change, and some varieties are bred for a specific colour palette.

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White Hydrangea Flowers

White hydrangeas do not change colour (Image: Getty)

The first thing you need to do is test the pH of your soil. Acidic soil (lower pH) will yield blue flowers and alkaline (higher pH) will give you pink flowers. 

You can buy a soil test kit on Amazon for £12.99 or from B&Q for £6.99 to determine the pH of the soil.

Once you know the general pH of your soil, you can adjust it to get pink or blue hydrangea blooms.

So what can you use to alter the colour of your hydrangeas? Taking to the Hydrangeas in the UK Facebook page, one gardener shared a photo of her “beautiful” hydrangeas bursting with vibrant blue blooms and claimed it was all down to one kitchen scrap item.

detail of a blue Hydrangea or hortensia flowers (Hydrangea Macrophylla) with blurred background

Coffee grounds can turn hydrangeas blue (Image: Getty)

Shanta Patel wrote: “This was a few years ago. Fed with coffee grounds.” she claimed that the plant was originally pink when she bought it from Ikea.

When asked how to apply the coffee grounds to the plant, Shanta said: “Add a layer [of used coffee grounds] on top every month and water it in.”

Shanta was also asked how long it took for her to turn her pink hydrangeas blue, and she claimed she saw results “within the first year”.

To maintain the acidity of your soil, gardeners can also use orange peels, eggshells, or peat if possible. 

Orange peel in soil

Orange peels can be used in place of coffee grounds (Image: Getty)

For faster results, gardeners can turn to the help of aluminium sulphate to turn their pink hydrangeas blue.

Gardeners can pick up the Trustleaf 1kg Tub Aluminium Sulphate from Amazon for £9.90. This product has received many great reviews from customers who have turned their hydrangeas blue and kept them that colour.

Alternatively, gardeners can purchase the Hydrangea Colourant from Thompson & Morgan for £5.99 which also changes pink hydrangeas to blue.

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