Plan the perfect garden with our interactive tool →

What Does Potassium Do for Plants?

Forest Ferns
PauuletHohn/iStock/Getty Images

Potassium is an essential element for plant growth. It is commonly applied to gardens, lawns and orchards as part of a regular fertilizer program. Garden potassium, usually in the form of potash, helps plants use water and resist drought as it regulates overall plant growth and health. Potassium is especially important to edible crops and enhances the size and quality of fruits and vegetables.

Potassium Problems

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

  • Potassium is an essential element for plant growth.
  • As potassium-deficient plants grow, the leaves curl along the edges and often appear dry, white-spotted or crinkled at the edges.

Nutritional Boosts

Potassium is a common mineral in soil, but often only a fraction of this potassium is available for plants. Some forms of potassium are easily absorbed for plant growth. Other potassium forms are 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.

Application Options

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

  • Potassium is a common mineral in soil, but often only a fraction of this potassium is available for plants.
  • Solid, granular fertilizers are scattered around garden plants or spread on lawns and watered in.

Potassium Effects

Potassium in commercial fertilizers is water soluble, meaning it readily dissolves in water and can be absorbed by the plant roots. Potassium controls plant stomata, the cells that control water. Without enough potassium, the stomata do not efficiently use water and the plant becomes 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.

Healthier Plants

Potassium grows healthy lawns by promoting green sturdy plants on deep roots. It aids roses (Rosa spp.), hardy in U.S. Department of Agriculture plant hardiness zones 4 through 11, 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 (Solanum tuberosum) need potassium for tuber growth. Potassium regulates plant growth so that harvested fruit is fully formed, high quality and has a better shelf life for consumers.

  • Potassium in commercial fertilizers is water soluble, meaning it readily dissolves in water and can be absorbed by the plant roots.
  • Without potassium, the plant cannot cycle the nutrients to feed roots, leaves and fruits.

Related Articles

Active Ingredients in Miracle Grow
Active Ingredients in Miracle Grow
Nutrients Needed for Hydroponics
Nutrients Needed for Hydroponics
How Does Miracle-Gro Work?
How Does Miracle-Gro Work?
What Minerals Does a Plant Need to Grow?
What Minerals Does a Plant Need to Grow?
How Do Different Fertilizers Affect Plant Growth?
How Do Different Fertilizers Affect Plant Growth?
The Effects of Phosphate on Plants & Water
The Effects of Phosphate on Plants & Water
Ingredients in Miracle Grow Plant Food
Ingredients in Miracle Grow Plant Food
What Does Phosphorus Do for Plants?
What Does Phosphorus Do for Plants?
Potassium Nitrate Effects on Plants
Potassium Nitrate Effects on Plants
What Nutrients Do Flowers Need to Survive?
What Nutrients Do Flowers Need to Survive?
Importance of Water in Plant Life
Importance of Water in Plant Life
What Does Ironite Do for Lawns?
What Does Ironite Do for Lawns?
Directions for Using Seasol
Directions for Using Seasol
Can Plants Survive on Other Liquids Besides Water?
Can Plants Survive on Other Liquids Besides Water?
Three Components of Fertilizers
Three Components of Fertilizers
Water Effect on Plants
Water Effect on Plants
The Effect of Fertilizers on Radish Growth
The Effect of Fertilizers on Radish Growth
Why and When to Use Fertilizers High in Potassium
Why and When to Use Fertilizers High in Potassium
Why Does Over-Fertilization Kill Plants?
Why Does Over-Fertilization Kill Plants?
Fertilizers Used for Wheat Growth
Fertilizers Used for Wheat Growth
Garden Guides
×