I have never grown leeks before, but this year I will. Leek is in the Alliaceae family. Other plants in that family are onions and garlic. Unlike the bulb that onion and garlic produces, the lower part of the leek is a tight bundle of leaves. The lower part is usually blanched in the garden by gradually covering the lower part with soil. I'm sure you've seen leeks at the store with their pale grit filled lower part.
I've grow celery before and it is another vegetable that requires blanching. Celery plants are planted in a trench and according to the gardening book [Encyclopedia of Organic Gardening, 1978 Rodale Press] that I am reading, leeks too are planted in a trench that is six inches deep.
Encyclopedia of Organic Gardening
Encyclopedia of Organic Gardening also says that leeks tolerate a mildly acidic soil. I've not had my soil tested, but, based on the weeds that flourish, it seems to be a least mildly acidic. We will see how well they grow in my garden. Over the season, I plan to note their progress.