Allotments 4 All

Half my leeks have bolted, can anyone shed any light on hat's gone wrong? They are an autumn harvesting variety "Monstrueux de Charentan".

They were sown in mid-march and planted out on 1st May into a clay soil with plenty of compost dug in. I applied phosphorus fertiliser and a liquid tomato feed about 2 or three days later because testing showed the soil deficient in P and K.

They were fed liquid seaweed at midsummer and nothing else since then except some liquid phostrogen a couple of days ago. my suspicion is too much potassium but I don't really know.