Potassium, Potassium Deficiency, Nutrient Deficiency, Mineral Deficiency
In plants, potassium is necessary for mechanisms controlling water loss and retention. It also assists in the absorption of carbon dioxide and the creation of energy due to its involvement in ATP production (Adenosine Triphosphate). Potassium deficiencies arise when soils are light and sandy, and nutrients are easily leached. Likewise, soils which are chalky or peaty, or those who are low in Clay, can be affected. Gardens growing lots of leafy vegetables, tomatoes or beans may require additional potassium supplements, too. Please note that scorching of the leaf margins can occur when plants are damaged by heavy winds and pollutants, including salt spray from the sea. Additionally, symptoms of a potassium deficiency are similar to those of a calcium-deficient plant. For this reason, other external factors influencing garden plants should be taken into consideration before diagnosing one of these plant problems.
Symptoms can vary depending on plant
Browning or scorching of leaf margins
Brown spots appear underneath leaves
Leaves begin to turn a blue-green colour
Yellow spots or marks begin to form between the leaf veins
A stunt in growth may be experienced
Tomatoes ripen unevenly
If it is solely potassium that's lacking, you can apply sulphate of potash during planting, using a rake to mix in thoroughly. If soil media lacks both potassium and nitrogen, NPK fertiliser of an appropriate ratio can be added to the soil media as per manufacturers instructions.