I am often asked if homemade sprays are safer alternatives to commercial pesticides. My answer is always NO! Apart from being illegal in the EU you never of the unintended consequences of making a spray.
The real answer is to create a garden that achieves a natural balance and accept that every year there will be some losses. In other words, stay cool and work with ‘nature’.
In our old garden we did achieve that balance. It took a while but eventually we had few problems. In the first year Gooseberry Saw Fly stripped a bush but never they came back. There were occasional black fly infestations on broad beans but nothing serious. We grew a potato variety called Sarpo Mira which never had blight – it is the most blight resistant spud in existence and was bred many years ago using conventional techniques.
Part of the reason for the lack of aphids was the nettles that surrounded the plot. They the perfect place for Ladybirds to lay their eggs early in the season. Ladybird larvae are voracious predators of aphids. They look scary but they really are your friend.