How do sunflowers turn back at night, and why do they always face the sun?

1. How to turn back at night

After the sun goes down, there is no sunshine. It will swing back slowly, rather than suddenly turning back as rumored. When there is no light, the auxin in its body will rearrange itself and be distributed relatively evenly, allowing it to slowly return to its starting position. At about 3 o'clock in the morning, it has turned back to its original position and will face east again, waiting for the sun to rise and start a new day of moving with the sun.

2. Why do we always face the sun?

From the time its buds begin to grow until the flower disk blooms, it will face the sun in order to absorb sunlight and obtain nutrients. The auxin on its back will increase, stimulating the cells on the side facing away from the light to slowly elongate, so that they will rotate with the sunlight. However, after the flower disk blooms, it will no longer rotate with the sunlight, but will instead face east to obtain nutrients.