Plant them in much deeper holes!

Try planting them in trenches, and as they grow fill the trenches in. The white part is where they didn't get any sunlight.

Thanks folks you have confirmed what I thought!

Was in a hurry this morning, but the way we grow them is to drop the pencil thickness babies into a hole made with a long handled dibber (Actually the broken shaft of a spade). The hole is about 9 inches deep and 1.5 inches across. We do not trim the roots or leaves of the leek, but some people do, personal preference. Fill the hole with water, that is enough to cover the roots with soil and stand back. You can drop a few plant food tablets into the hole if you like.

Thanks for that Owdboggy, all I need to do now is vandalize my wifes spade!!!