How does a seed become a plant?

A bean seed lies dry and silent in the palm of your hand. Put it on damp cotton wool and within a few days it splits its coat, puts down a root and opens its leaves; a few months later it has become a plant hundreds of times heavier than itself. Every step of this transformation hides another question: what wakes the seed up, how does water climb without a pump, and where does the plant find all that mass?

The journey begins with germination: you'll see how water, warmth and oxygen wake a seed, and why lettuce refuses to germinate in the heat. Then you'll follow water's path from the root hairs up to the leaves, and discover how photosynthesis lets a plant build its mass from the carbon dioxide in the air. In the plant lab you'll set the light, water and temperature yourself and find out which factor is limiting growth.

In the last two steps you turn your gaze into the soil: the billions of living things in a handful of earth, the fungi that live in partnership with roots and the bacteria that fix nitrogen from the air. By the end you'll be able to explain why farmers rotate their crops, and what a huge team effort it is for a seed to become a plant.