How Seasons Affect Plants

Core Idea

Plants change with the seasons. In spring, seeds sprout, buds open, and plants begin to grow. In summer, plants grow their biggest and many produce flowers and fruit. In autumn, many trees lose their leaves (which often change color first), and plants begin to slow down. In winter, many plants go dormant -- they are still alive but stop growing until spring returns. These changes happen because plants respond to temperature and the amount of sunlight.

How It's Best Learned

Observe the same tree or plant throughout the school year and photograph or draw it each month. Plant seeds in spring and track their growth through the seasons. Collect fallen leaves in autumn and discuss why trees drop them. Compare deciduous trees (which lose leaves) to evergreen trees (which keep theirs).

Common Misconceptions

• Trees that lose their leaves in autumn are dead. They are dormant -- alive but resting. The roots and trunk are still living.
• All plants lose their leaves in winter. Evergreen trees keep their leaves (needles) year-round.
• Leaves change color because they are dying. Leaves change color because the green pigment (chlorophyll) breaks down, revealing other colors that were there all along.

Explainer

Plants do not experience seasons the way people do -- they cannot put on a coat when it gets cold or turn on a light when days get short. Instead, they change with the seasons. These changes are some of the most visible signs of the seasons passing.

In spring, plants wake up. Seeds that have been sitting in the soil through winter begin to sprout. Trees grow new buds that unfurl into fresh green leaves. Flowers push up from the ground. Everything starts growing because spring brings warmer temperatures and longer days with more sunlight -- the two things plants need most.

In summer, plants are at their most active. With long hours of strong sunlight and warm temperatures, they grow fast, produce flowers, and many develop fruit or seeds. A garden in summer is bursting with green growth. This is the season when plants do most of their work -- capturing sunlight, building stems and leaves, and making the seeds that will become next year's plants.

In autumn, something changes. Days get shorter and temperatures start dropping. Many trees respond by pulling valuable nutrients out of their leaves and storing them in their trunks and roots. As the green pigment (chlorophyll) in the leaves breaks down, other colors that were hidden underneath -- yellow, orange, red -- are revealed. That is why autumn leaves are so colorful. Eventually, the leaves dry out and fall off. The tree is not dying; it is preparing for winter.

In winter, many plants enter a resting state called dormancy. They are still alive, but they stop growing. Without leaves, a tree uses very little energy and very little water -- just enough to survive until spring. Look closely at a winter tree and you will see small buds on the branches. Those buds contain next year's leaves, packed up tight, waiting for the warmth and sunlight of spring to trigger them to open.