Traditional farms were not weed-free. Weed seeds are present in the soil, in the compost that you spread, and even mixed in with the seeds that you are planting – which is probably the case with poppies. Over time, however, the plants that one does not want to see in the fields – such as nettles, thistles, brambles, vetches, and docks – are gradually exiled to the fringes of the farm, and other plants that grow happily beside and amongst the crops become a fixed feature in the fields.