Hydrangeas can flourish with a surprising kitchen item many tend to throw away, promising bigger and more vibrant blooms during summer.

Used coffee grounds are a gardener's secret weapon for these plants, packed with nitrogen a key nutrient that boosts leaf growth and is essential for flower production.

Without adequate nitrogen, hydrangeas can suffer from yellowing leaves, stunted growth, and lacklustre flowers, or they may fail to bloom altogether.

Garden designer and founder of Susan Said What, Susan Conforte McNeill, has revealed that coffee grounds not only act as an excellent fertiliser but can also naturally alter the colour of hydrangea blooms and ward away slugs.

She explained: “I’ve learned that turning a hydrangea blue naturally, with no harsh chemicals, can actually be easy. Just add... coffee!”

However, before sprinkling your hydrangeas with coffee grounds, it’s crucial to check the soil's pH level. While acidity is beneficial for hydrangeas, too much can damage the plant.

Susan advises that by checking the pH level, gardeners can adjust their soil accordingly, ensuring their hydrangeas are set to produce big, beautiful blue blooms” come summertime.

She added: “Soil pH testing kits are widely available at speciality home and garden stores, big box retailers, and even on Amazon.”

You can easily give your hydrangeas a little boost by mixing coffee grounds with water and placing the mix into the soil. If you have leftover filtered coffee, don’t waste it; just pour it on the soil instead.

Susan shared her garden wisdom, saying: “To adjust the acidity of the soil, coffee grounds are the simple, easy and free solution.”

She added: “The increased acidity from coffee grounds makes it easier for the plant to absorb naturally occurring aluminium in the dirt, resulting in bigger beautiful blue flowers.”

It’s not a quick fix, though as this process should only feature in your gardening routine once a month. But regular application will mean robust and vibrant blue flowers blooming in summer.

But that’s not all coffee grounds can improve soil drainage and aeration while they feed your flowers. Plus, pests or pets will think twice before approaching your precious hydrangeas.

Susan further explained: “Many gardeners swear that coffee grounds are also helpful in keeping slugs and snails away from plants. Similarly, the coffee is helpful as a cat repellent and will keep neighbourhood cats from using your flower beds as a litter box.”

Wrapping up with a cheeky tip, Susan said: “So, brew an extra pot and sit down to a delicious cup of Joe with your plant.”