Hydrangeas need to be fed one kitchen scrap to grow bigger this summer

Gardening experts are raving over a simple trick that can give your hydrangeas an extra edge this summer, and it involves just one household item - used grounds. Pyracantha's whizz, John Moore, has spilled the beans on how a sprinkle of coffee can do wonders for your hydrangeas, boosting their water absorption.

He shared: "Hydrangeas respond well to coffee grounds in the soil. Most people use coffee grounds to help change the colour of their hydrangea blooms from pink to blue as it makes the soil more acidic but it's also useful to retain moisture in the soil between watering."

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Not only can coffee turn hydrangea blossoms a brilliant blue or delicate purple hue, but it doubles as a slug deterrent too, with the pesky critters recoiling at the scent and texture of caffeine remnants.

Ensure you integrate coffee grounds into the soil around your hydrangeas or fold them into your compost heap if garden aesthetics are a concern - though remember, acidic soil isn't everyone's cup of tea, particularly other plants'.

To keep tabs on just how much your soil's pH has dropped thanks to the coffee boost, regular checks using a pH soil tester are advised, but usually, only a modest amount is needed to get the desired effect on hydrangeas.

John reiterated: "If your starting pH is neutral (7) you don't need to add a huge amount of coffee grounds.

"If you have a start point on the alkaline side of the scale, however, you need to take your soil through the neutral point (ph 7) to the acid side.

"This takes more work and more coffee grounds and is not always very effective. You're "looking for pH 6 to pH 6.5 to get the best blue flowers."

Coffee grounds act as a soil amendment to help hydrangeas retain water which will make their flowers much bigger and more abundant, reports .

John said: "Adding coffee grounds, which are an organic matter, to your soil adds nitrogen and in turn, this helps the stem, leaf and root development of your plants.

"The soil retains moisture, keeping the roots wetter for longer. If your soil is a bit sticky, add the coffee grounds to your compost to help the soil drain much more easily."

However, only use coffee grounds in moderation as you only need to feed each hydrangea plant one cup of coffee grounds each month to get the benefits.

The nitrogen in coffee is great for the roots which is how it helps the plant hydrated, but too much fertilisation can cause a nitrogen imbalance will cause the leaves to turn yellow and could stunt the hydrangea's growth so make sure not to overdo it.