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How Plants Use Water

A person waters flowers.

Water is an essential nutrient for plants and comprises up to 95% of a plant’s tissue. It is required for a seed to sprout, and as the plant grows, water carries nutrients throughout the plant. Water is responsible for several important functions within plant tissues. 

Water is necessary for photosynthesis, which is how plants use energy from the sun to create their own food. During this process, plants use carbon dioxide from the air and hydrogen from the water absorbed through their roots and release oxygen as a byproduct. This exchange occurs through pore-like stoma on the leaves.  

Water is evaporated on the leaves, as well, in a process called transpiration, which keeps plants from overheating. Warm temperatures, wind and dry air increase the rate of transpiration. As water evaporates through the leaves, more water is pulled up through the roots of the plant.  

Nutrients and sugars from photosynthesis are dissolved in water and move from areas of high concentration, like the roots, to areas of lower concentration, such as the blooms, stem and leaves, for growth and reproduction.  

Water is responsible for cell structural support in many plants, creating a constant pressure on cell walls called turgor, which makes the plant flexible yet strong and allows it to bend in the wind or move leaves toward the sun to maximize photosynthesis. 

Low moisture will cause browning of plant tissues and leaf curling, eventually leading to plant death.  When watering garden plants, it’s important to provide a thorough, deep watering rather than frequent, light watering to encourage deeper root growth.


By Jodi Richmond, WVU Extension Service Agent – Mercer County