Hydrangeas are some of the most sought-after flowering shrubs due to their incredible blooms and versatile nature. One of their unique aspects is their ability to change colour, especially shifting from pink to mesmerising shades of purple and blue. On sunny or cloudless days, blue and purple accents will kick your garden up a notch for a gorgeous scene.

When you hear of the magical, colour-changing abilities of these enchanting plants, gardeners are actually talking about a specific variety called hydrangea macrophylla, or "bigleaf hydrangea". Bigleaf hydrangeas are known to bloom in shades of pink, blue, purple or white. While white varieties will remain pure and untouched by colour regardless of what you do, pink, blue and purple hues can be influenced by the soil they grow in.

The secret to changing the colour of hydrangea flowers isn't what's applied to the blooms themselves; it has to do with the chemistry of the soil.

The more alkaline the soil is, the pinker the blooms will be. At neutral pH, some varieties remain pink while others will start showing hints of blue with lovely shades of lavender.

Blue hydrangeas bloom in acidic soils, usually with a pH of 5.5 or less, while purple hydrangeas bloom when the soil pH is at 6.5 to seven.

Taking to Facebook, one woman shared how she turned her once pink hydrangeas "multicoloured" with stunning hues of blue and purple, and it's all down to the power of coffee. This is a simple task that shouldn't take more than 15 seconds out of your day.

Alongside a photo, Christina Edwards posted: "Apparently, my hydrangeas appreciate my morning coffee grounds. The multicoloured hue is due to the extra acidic soil from the coffee!"

When asked in the comments section how this works, the gardening fan said: "Yes, coffee is acidic. The colour of the hydrangeas is correlated to the pH of the soil, and more acidic soils produce bluer blooms."

Speaking about how often she uses this kitchen scrap ingredient on her hydrangeas, Christina said: "I don't add coffee every day, it's at most three times per week.

"There are three bushes and they're all outside, and eventually the coffee grounds decompose into fertiliser, and the rainwater dilutes the coffee.

"I brew my coffee in a coffee press, so the grounds left at the bottom of the coffee press, I just pour them onto the soil! I don't mix it in, I just let Mother Nature take care of the rest."

Fellow gardening fans shared pictures of their hydrangeas turning shades of blue and purple after using coffee grounds.