Summer is a season that affects the world outside of the tropics. Areas beyond the tropics have seasons related to how warm it is. So they have spring, summer, autumn/fall, and winter.
The changes in length of day, and the warmth of the air has a great effect on plants and animals. Most plants do not grow in winter because it is too cold. Some animals hibernate because there is much less plant food in winter and early spring. But as the days become a little longer, those plants that have stored up reserves in bulbs begin to send out shoots and then flower. Snowdrops, crocuses, daffodils and so on, are all bulb flowers.
Most deciduous trees put on leaves towards the middle or end of spring. By this time the bulb plants have flowered, set seed and died back. The last trees have their leaves by the time summer begins.
For many people, summer is a time of holidays by the sea, a time of sunbathing and doing things outdoors that can't be done in the colder parts of the year. Summer is mostly after the longest day. This is because summer is based on seasons of warmth, not day length. It takes time for the air, ground and sea to warm up each year, and they lag several weeks behind the day when the Sun is highest in the sky. For most places the hottest day is about July 16. Once the ground has warmed up, the fact that the Sun is lower in the sky is less important, so summer goes through to September.
Plants have grown in spring, and during summer they mostly spend time setting seed. You see this in fields where the cereals like wheat turn from green to gold. Plants need a lot of water in spring when they are growing more leaves, but in summer they can tolerate long periods without rain. In fact, they set seed better that way. So why do you have to water plants in your garden in summer? That is because many of the plants in your garden come from other parts of the world where rain is needed all year. Many garden plants grow natively in the tropics. That is why you can't plant them out until the last frosts have gone.
