It’s easy to diagnose a potassium deficient plant because the leaves are….

Mottled, look grayish, or the edges turn yellowish-brown and curl. Potassium is the third of the three most important plant nutrients, the K in the N-P-K formula on fertilizer bags. To add some to your soil, spray it with fish emulsion or sprinkle a light dusting of dry wood ashes around your plants.