Three discarded ingredients in your kitchen could turn hydrangeas beautiful shades of 'blue and pink’

hydrangea and coffee grounds

Natural ingredients could influence the hues of your hydrangea blooms

Solen Le Net

By Solen Le Net

Published: 14/04/2024

- 10:00

Updated: 14/04/2024

- 10:11

The colour of two hydrangea varieties could be changed with eggshells and ground coffee

Hydrangeas come in all shapes and sizes, producing an abundance of petals that are well-suited to different environments.

Their characteristic blue and pink hues reflect the acidity levels of the soil they’ve emerged from, with blue flowers growing in acidic soil while pink hues come from alkaline ground.

Conversely, neutral soil is key for gardeners who want to turn their hydrangeas a deep purple colour.

Gardeners have claimed that, with prolonged use, several natural ingredients can change hydrangea colours, including coffee grounds, eggshells and vinegar.

purple hydrangea blooms

Hydrangea flowers come in various shades of blue and purple


“Some gardeners have claimed that adding coffee grounds to the soil turns their hydrangeas blue,” Craig Morley, a gardening expert from Budget Seeds, told GB News.

This is because the coffee grounds will make the soil more acidic, allowing the hydrangea plant to absorb more aluminum from the soil.

The expert continued: “Crushed eggshells can reportedly be used to turn hydrangeas pink. [...] The shells will slowly break down and reduce the acidity of the soil, which will make it harder for the hydrangea to access aluminum present in the soil.”

Some gardeners have claimed to turn their hydrangeas blue by adding vinegar to the water they use to water their soil, according to Craig.

Patience is key with these methods, as natural ingredients need months to alter the pH levels of the soil.

Craig explained: “Changing the pH level of the soil in your garden can take around three months, or potentially up to 18 months.

“Once the pH level has increased or decreased enough to change the colour of your hydrangeas, you will still need to keep applying whatever you were using to the soil so that they retain this colour.

“You can try adding it to the soil when you first plant hydrangeas, but you are unlikely to see a colour change from this until the following year.

“The colour of certain varieties of hydrangea (bigleaf or mountain hydrangeas) can be changed and it is thought that is related to the pH of or level of aluminum in the soil.”

Traditional methods to change soil pH levels have involved adding aluminum sulfate to the soil and maintaining low levels of phosphorous, moderate levels of nitrogen, and high levels of potassium.


Hydrangea plants

The colour of hydrangea blooms is determined by the acidity of soil


To give the sepals a pink hue, the recommended ingredient is garden lime, an active component made predominantly of calcium carbonate.

It comes as an expert recently told GB News about the benefits of using molasses to encourage prolific flowering of their plants.

The sweetener has been lauded by many experts as a fertiliser because it contains many of the minerals essential for plant growth.

What’s more, its unique sticky texture helps minerals latch onto plants and infiltrate their root system.

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