Nutrient Basics -- Potassium

Potassium (K) is important for the formation of flowers, fruit, and leaves. It also helps photosynthesis at low light levels and in internal water regulation. I have read it improves flavor in fruit, vegetables and flower color. Potassium is also linked to insect damage protection, disease and frost protection. Lack of potassium will reduce yield and quality.

Signs of a Potassium Deficiency --Older leaves are initially chlorotic becoming mottled or spotted, root systems are poorly developed and, fruit ripens unevenly. These symptoms will first apparent on the tips and margins (edges) of the leaves. Stem and branches may become weak and easily broken, the plant may also stretch. The plant will become susceptible to disease and toxicity. Also, a potassium deficiency will result in poor storage qualities (storage of herbs link)

Potassium can be limited in plants by too much sodium (Na) which displaces potassium, causing a deficiency. Sources of high salinity are: baking soda (sodium bicarbonate "pH-up"), too much manure, and the use of water-softening filters (which should not be used). If the problem is Na, flush the soil. K can get locked up from too much Ca or ammonium nitrogen, and possibly cold weather/ temperatures.

Organic sources of potassium are kelp or any seaweed and wood ash. Potassium toxicity is rare so make sure to give plants potassium in all stages of growth. I do not like to use fertilizers that lack potassium as the sole source of nutrients.

See my post on how potassium can affect pH

Good Growing,
Dr. E. R. Myers

No comments: