During the spring, the light part of the day grows longer and the temperature becomes warmer. The growing season of plants begins when the air temperature rises above +5 °C during the day. This occurs between April and the beginning of June.

In Southern Finland, many plants wake up even before the beginning of the actual growing season. For example, liverleafs often already flower during the middle of April. The first flowers you can find in the spring belong to perennial plants.

The liverleaf flowers early in the spring.

Broadleaf trees begin to develop and open their buds when the temperature rises above 0 °C. The buds develop into photosynthetic leaves and reproductive flowers containing stamens and pistils.

The rising temperatures also cause hibernating animals to wake up. Many reptiles, such as adders, begin to move only when the daily temperature rises well above zero. Similarly, mammals such as bears and hedgehogs wake up when the temperature grows warm enough.


The mountain hare changes its winter coat into a summer coat when the light part of the day grows longer.

Mammals change from their heavy winter coats into lighter summer coats when the light part of the day grows longer. This is why you can sometimes see a white-coated mountain hare even months after the snows have already melted.