MGG and I were looking over the plants in the plant scheme greenhouses and noticed that the sweet corn leaves have gone very yellow. We were of the opinion that they weren't in a saleable condition, but not quite sure what was wrong with them. It could be nutritional, they have been in the modules for a while now and may have outgrown their pots. Could be over watering, could be under watering, your guess is as good as mine. I have an empty 4X4 raised bed which I could put them in to see if they would recover, so I leapt (!) over the fence (they are in the empty greenhouse next to mine), collected the worst affected plants and planted them in my garden.
They have come straight out of the greenhouse so I put some fleece over them for the first few days.