Garlic Water For Plants: Easy DIY organic pesticide:•1 Small Head of Garlic 1 whole head of garlic in a blender. smooth as possible. 2.Add two cups water to the blender and pulse. 3.Pour the mixture into a glass container and sit covered in a dark place for one day. 4.When ready to apply, strain off all the solids and dilute with more water until you have a gallon's worth of solution.