Received wisdom tells us that polycultures, a farming technique that involves growing multiple crops in the same area, can be excellent for biodiversity by enhancing the number of wild species that occupy the land. However, biodiversity is not ‘one thing’ — we don’t yet know ‘what’ biodiversity polycultures can support — common species? Rare species? How do pests and beneficial species trade off in polycultures? Is there any benefit of polycultures for biodiversity in the surrounding landscape? And importantly — what should we be aiming for? This panel brings together four people working on biodiversity in polycultures to openly discuss with you all the key question: what biodiversity do we actually want?