I lost my first lot in the floods last year, sowed a new lot in June, and they're still baby leek size. Not surprising really. I'm going to throw them out and plant more next month. If you want a decent white bit on leeks, shove a dibber in as far as it will go, drop the leek in, and fill the hole with water. As long as the leaves are poking out of the top, it will be fine.