Potash fertilizer can be used with all plants that do not grow well in acidic soil and in areas where the pH in the soil is alkaline. Potash should not be used on plants such as azaleas, hydrangeas and rhododendrons.
For plants that tolerate potash fertilizer, the result is larger, healthier growth that produces bigger flowers and vegetables. The easiest way to determine if potash will work in a garden is to do a soil test. If the soil needs potassium, potash is a good option.
Adding potash to plants that do not require extra potassium results in fertilizer burn, which gardeners may avoid by watering immediately after applying fertilizer. Because potash is a granular, synthetic fertilizer, it works well for perennials and vegetables. The potash should be applied in the way recommended on the package.
Potassium promotes vigorous growth and helps plants stay resistant to disease. When used on lawns, potassium provides a winterizing effect to improve cold weather hardiness. Potassium promotes overall plant health when used correctly.
For best results, potash should be used in combination with nitrogen and phosphorous when required. Liquid potash gets absorbed by the plant almost immediately, making it a good choice for potted houseplants that eventually take all the nutrients from their potting soil.