Why do plants need water?

A few days ago, we noticed that one of our little pumpkin plants on the window sill had wilted. The soil looked dry, so we watered the plant, and after a few hours, it was standing lovely and straight again. This got us wondering why plants need water.

Why do plants need water?

Plants need water to germinate.

We saw this with our bean in a jar. Water is needed to activate the process of germination, it also softens the seed making it easier for the plant to break through.

Photosynthesis

Photosynthesis is the process by which plants make energy to grow. Photosynthesis requires sunlight, water and carbon dioxide. We demonstrated what happens when a plant cannot photosynthesise when we made our cress caterpillar.

Nutrient transfer

Plants need water to absorb nutrients from the soil.

Transpiration

Transpiration is the process by which water moves up the stem of a plant from root to leaf when water is lost from the plant due to evaporation occurring at the leaves. This continual flow of water and nutrients keeps the plant's cells firm. If the cells become short of water, the plant starts to wilt.

We can demonstrate transpiration by placing white flowers in coloured water, the water travels up the stem to the petals which become coloured like the water.