Potash is a collective name for potassium salts that help grow healthy plants. Potash is good for fruit and  flowers helping thebbalance with nitrogen to improve disease protection and enhance flower colour.

Potassium sulphate widely used as a quick acting source of potash. Ideal for tomatoes, peppers and easy to mix and apply from a liquid.

Potassium nitrate is quick acting if you need a boost to nitrogen and potash at the same time. Like p. sulphate it helps develop fruit and can be sprinkled around the roots of fruit trees

Potassium chloride is a cheap form of potash that is a bit out of favour as it is less suitable for some root crops and soft fruit.

Home made potassium rich fertilizers can be made from comfrey leaves or wood ash. Soak comfrey leaves in water to make a vile smelling potash rich feed. Burnt wood ash contains potash but of varying quality and longevity so it may be best added to your compost heap.