When are leek seeds ready to harvest?

How do leek seeds / the flower look like when it is ready to harvest the seed? I have one flower that already grows small leeks on its head!

That sounds like a clumping or walking onion to me. I've never seen a leek do that.
Leek seed heads are like onion seed heads: harvest when the seeds are black and dry.

Oh that means I still have to wait a bit they are still whitish purple. Yes it is definitively a leek I know it. It has been pretty wet recently and because the others
were sprouting I thought it is time to harvest them. That is a long wait especially because they don't keep very long. I guess I will plant them into a bed and sell leek seedlings after giving away a ton of seeds.

Check out - http://www.wikihow.com/Grow-Leeks These has helped me a lot!! Hope this will help you too.

After flowering, the tops of our leeks became dark in color and dray and the seeds dropped off pretty when rubbed or gently shaken.