[waliz]

most of my leeks have a seed head on them .what caused this and how can I cure it

[ANHBUC]

Welcome to the site waliz, I have moved your topic to Grow Your Own.  Hopefully you will get plenty of advice.   

[mumofstig]

when did you sow/plant them?

[Totty]

Could they have gone short of water during the hot spell? Leeks can often bolt if they dry out in hot conditions.

Totty

[solway cropper]

Once they've bolted (gone to seed) there is no cure. Nip out the seed/flower stalk, unless you want to keep the seed, and leave them to grow. You can still eat them but they'll have a hard core down the middle.

[JayG]

I would guess that Totty's explanation is the most likely - shortage of water will stress them in hot spells and trigger premature production of flower heads, although any sort of stress can do the same thing.

I had about half of mine bolt 2 years ago, and none last year (and none so far this year.) Same variety, same cultivation method - sometimes the life of a plant is just too complicated for we mere humans to fully understand! :

If you cut off the seeds heads as soon as you see them the stalk in the centre of the leek shouldn't be too tough, although it will be visible. I have no problem eating them as they are, although I suspect some people get their dissection kits out and surgically remove the offending items before cooking!