In 2022, parachutist Luigi Cani dropped 100 million seeds over the Amazon rainforest while skydiving. He did it to raise awareness about deforestation and help regrow the forest. But there has been little scientific follow up to see whether it worked. So, today, we talk to restoration ecologist Pedro Brancalion about the surprising complexity involved in regrowing a forest, and when dropping seeds from the sky – by people or by drones – could work.