Hydrangeas are a great plant to add to your garden in the spring ready for a burst of colour to come through when they bloom in mid-summer.

The exact timing bloom can vary depending on the variety and , but they typically flower in mid- to late summer and their striking cone and ball-shaped flowerheads make for a striking garden display. The flowers bloom in several different colours, but the most popular shades are blue, pink, purple and white. But these plants are especially unique in the fact that many can change the colour of their flowerhead, particularly the hydrangea macrophylla variety.

The colour change is influenced by the pH levels of the soil, with acidic soil producing blue and purple flowers and alkaline soil resulting in pink or red blooms. White varieties generally stay white regardless of the soil pH levels.

If you're particularly fond of the blue variety and want to maintain in your garden throughout the summer, then there are ways to make your soil more acidic using natural ingredients. According to gardening experts, one way to do this is by adding orange peel to the soil around the base of the hydrangeas.

Orange peel is naturally acidic due to its high concentration of citric acid. As the peel decomposes into the soil, its organic acids are then broken down by microbes to release hydrogen ions, which then lowers the pH of the soil, making it more acidic. This is good news for acidic-loving plants like hydrangeas which thrive in these conditions, and this low pH level can then encourage blue blooms.

The orange peel is also rich in nutrients like nitrogen, phosphorus and potassium which can help make the plant grow bigger and stronger, improving its overall health. If you don't have any oranges to hand, the peel from lemons, limes and grapefruits will work just the same, as will coffee ground or crushed egg shells.

Bay Ave Plant Company explains: "To make your blue flowers more pink or your pink flowers more blue, you need to change the acidity of the soil. Changing the pH of the soil is as easy as adding coffee grounds or a ground up citrus peel. Make sure to work this mixture into the soil around the base of the hydrangea plants.

"If you want your flowers to remain that beautiful blue or pale pink, the upkeep is easy. For blue flowers, simply fill a bowl with coffee grounds, orange peels, or even crushed egg shells. Keep the bowl in the kitchen and once it is full, bring it outside to feed the hydrangeas."

Gardeners should be aware that the process of turning hydrangeas a more vibrant blue won't happen overnight and will require some time and patience to produce the colour, so if you want to give the plant an extra helping hand, adding aluminium sulfate to your soil as well can really help.

Eising Garden Centre adds: "To maintain the acidity of your soil, you can fertilise with acidic compost like orange peels, coffee grounds, eggshells, or peat.

"While you won't see results right away, these will help increase soil acidity in the long term, so that you eventually won't have any need for the aluminum sulfate."