Potassium plays a role in many aspects of plant growth and water transportation throughout a plant’s lifecycle, and is particularly important for bud growth.
If a plant is deficient in potassium it might not be immediately obvious because minor deficiencies can make plants grow taller than plants that aren’t deficient.
Symptoms of a minor deficiency begin to show as necrotic spots or browning on the leaf margins.
If the deficiency is more severe, the veins of the leaves will turn red or yellow, and the leaves will develop large chlorotic spots. Plant stems turn red.
To correct a potassium deficiency add kelp extract to the solution because kelp is high in potassium. Plant will recover in under a week.
Potassium deficiency is the least common macro nutrient deficiency for hydroponics.
If potassium is toxic, magnesium, iron, zinc, and manganese get locked out. Symptoms of a potassium toxicity can look like a deficiency of these other minerals making a toxicity diagnosis difficult.