Posted: 20/12/2013 at 12:32
Sorry, was in a hurry.
Plant the leeks in a hole as described above. Then as the stem elongates out of the soil wrap cardboard round the stem and pile earth round it. That way you get the length of stem below ground and in the cardboard to be blanched and reasonably soil free.
OR. Plant the leeks as you would any plant and put a cardboard tube round and earth up. Keep adding cardboard tubes as the plant elongates until it is as long as you want it to be.
Not that easy to describe in words. Bet there is a Video of doing in somewhere on the Interweb thingy.