Gardeners are being urged to spray washing up liquid on their gardens this year - to help banish pests which can destroy your plants and damage fruit and veg crops.

Washing up liquid, or dish soap, is a chemical-free and kill-free way to repel flies, aphids and caterpillars from plants in the summer.

Any centre is packed with expensive sprays, unguents and chemicals that promise to 'kill flies fast' or 'bug clear aphids' but the problem with these - aside from the expense - is that they can kill beneficial things in your , like bees, wasps, worms and moths, with their potent chemical mix.

That's why washing up liquid is the perfect way to protect your plants. It's cheap, it stops aphids, greenfly, whitefly and other pests, and it doesn't kill anything, just keeps them away.

Though washing up liquid sprayed directly onto aphids will kill them, the main treatment is that it coats the stems and leaves of plants with a slippy substance that protects them from insects. Flies like aphids and greenfly won't be able to land on the leaves and won't be able to feed from the stems, so not only do you get rid of the pests you directly spray, but you prevent others from leaching off your plants in future.

According to garden experts Thompson Morgan: "The most commonly used non-chemical remedy is to spray them with soapy water. You can buy insecticidal soaps but many people make up their own using a teaspoon of washing up liquid diluted in 3 litres of water.

"The aphids are unable to breathe under a coating of soap and subsequently suffocate. If you intend to try this, then be sure to spray on a dull day as spraying in full sun is likely to scorch the foliage."

BBC Gardeners' World adds: "Greenfly and blackfly are a natural part of the garden ecosystem and a vital source of food for many species of birds, including house sparrows. They're only a problem if they occur in large numbers. Large infestations can weaken plants and cause curling or distortion of affected growth.

"This can sometimes eventually kill the plant, especially young ones. Some aphid species transfer virus diseases between plants - many viruses cause a range of symptoms including mottled, streaked or distorted foliage, and weak growth. Viruses aren't curable, so infected plants should be destroyed. An additional problem caused by greenfly and blackfly is the sticky substance they exude, known as honeydew, which can become infested with black mould - this stops leaves photosynthesising and inhibits plant growth.

"Organic (chemical-free) sprays are based on plant extracts, plant oils or soft soap. These must be sprayed directly on the aphids in order to work, and often only persist for a short time so may need re-application."

According to Country Life blog, if you don't want to risk killing aphids, but simply encourage them to leave, you can dilute the washing up liquid doesn't kill the aphids, it just forces them to move off your plants. It says: "Put a litre of water in a spray bottle with one or two drops of washing-up liquid. Spray the water on the stem of the plant and this should get rid of the aphid cluster.

"The water and detergent mixture is completely harmless to the aphids. All that happens is the mixture is sprayed on their face, forcing the aphid to rub their eyes. When this happens they simply lose their grip of the stem and fall off as a result!

"One disadvantage to this method is that it has to be done daily, otherwise the aphids will climb back up onto your stem overnight."