What Does Potassium Do for Plants?

Potassium is an essential element for plant growth. It is commonly applied to gardens, lawns and orchards as part of a balanced fertilizer. Potassium, often called potash, helps plants use water and resist drought. It promotes healthy green lawn grass. Potassium is important to food crops and enhances the size of fruits and vegetables. Potassium is called the regulator of plants.

Identification

When plants do not have enough potassium, they have symptoms like stunted growth, poor flower development and lower quality fruit or vegetable harvest. Plant leaves may look scorched and curl at the tips. As the plant grows, the leaves curl along the edges and often appear dry, white-spotted or crinkled at the edges. Growth is slow. Wind or high temperatures easily damage the plants.

Significance

Potassium is a common mineral in the soil. Only a fraction of this potassium is available for plants. Some potassium is easily absorbed for plant growth. Other potassium is not usable by plants. Gardeners and agriculturists discovered that if potassium in the soil is not in a plant-friendly form or if the soil is potassium-depleted, other kinds of potassium can be applied as fertilizer for healthy plants.

Types

Potassium is commonly applied in solid or liquid NPK fertilizers. Commercial fertilizers list the three major chemicals in label percentages such as 5-10-5. The first number is Nitrogen (N), the second is Phosphorous (P) and the third is Potassium (K). Solid NPK fertilizer is granular and is scattered around garden plants or spread on lawns. Liquid NPK fertilizer is applied with spraying or watering. Potassium is sometimes applied through drip irrigation systems.

Function

The potassium in commercial fertilizers is water soluble, meaning it readily dissolves in water and can be absorbed by the plant roots. Potassium controls the stomata, the plant cells that use water. Without enough potassium, the stomata do not efficiently use water and the plant is not healthy. It becomes vulnerable to disease and heat stress. Potassium also aids the enzymes promoting plant life. Without potassium, the plant cannot cycle the nutrients to feed roots, leaves and fruits.

Benefits

Potassium grows healthy lawns by promoting green sturdy stems on deep roots. It aids roses and other flowering plants by encouraging strong stems and well-developed flowers. Farmers depend on potassium for healthy crop production. Plants rich in carbohydrates such as potatoes need potassium for tuber growth. The potassium regulates plant growth so that harvested fruit is fully formed, high quality and has a better shelf life for consumers.

Resources

• California Fertilizer Foundation