Which is better - roots deep in the earth or in a nutrient cocktail on a vertical farm? We hear about the biology of how salad crops are grown without using soil.

As part of our week focusing on salad, we visit a micro-farm growing micro-greens.

It's harvest time for broad beans, but one grower calls them “the forgotten vegetable”.

Presented by Caz Graham and produced by Beatrice Fenton.