Leeks are sold as small plants in single cell soil blocks. There are approximately 10-15 leeks per block.
To transplant into the garden, carefully remove the soil block from the container and gentle pull apart the wiry roots of the leeks. I like to push a hole into the soil with a dibber about 4 inches apart. If you don’t have a dibber I’ve used sturdy sticks, random kitchen utensils, the end of a shovel to make the hole. Make the hole deep enough so that about half the leek is above soil level. No need to fill in the hole. Simply water in the leek so the soil settles around the roots and you’re good to go!
This isn’t the only way I have grown leeks. Sometime I plant them just a little deeper than I normally would onions and walk away. I have never hilled my leeks, although you could if you so desire. Here are some helpful videos on planting out your leeks:
Allotment Diary – How to Grow Leeks (Planting Out): This guy plants his much farther apart than I do and I find it completely unnecessary to plant them this far apart. Also, remember than your leeks may be smaller than his so you may not need to make 6″ deep holes.
Charles Dowding – Grow Leeks from Multi-sown modules: I love this guys videos. I highly recommend checking out more of his videos.