Leeks gone to seed?

You could have a few problems actually. One, that its very possible in the packaging line that an ornamental allium seed, or 2, somehow got into your leek pkg. Or, that with the strange weather conditions this year, the plants were fooled into throwing up seed stalks instead of producing proper roots. It sometimes happens and you just have to accept these things. Try a fresh pkg of leek seeds for next year from a different supplier and you should do fine. Also, if the plant gets too dry it's also a signal to make seed instead of root.  Lots of manure and compost in the soil will both feed the leeks and retain moisture.