Last spring one of my community garden neighbors gave me her extra leek and shallot seedlings, and showed me how she grows leeks in a trench. To grow leeks with nice long white stalks, you need to keep covering the stalk with soil as it grows. Often leeks are planted level with the ground and soil is mounded up around them as they grow. My neighbor told me that she likes this trench method instead because she’s lazy, though you’d hardly think her lazy looking at her garden. She plants her leeks at the bottom of a trench, and then gradually fills it in as the leeks grow. The trench method is a bit more work at planting time, though I do think it makes things a little easier for the rest of the season.
This year I started my own from seed, and this morning I got them in the ground. Note to self for next year, plant the leeks before you start filling in the rest of the beds. I had terrible time trying to dig my trenches without stepping on the lettuce and beets I planted last weekend!
For a double row of leeks, dig a trench about 8 inches wide and 6 to 8 inches deep down the length of the bed.
Once you have your trench dug, carefully remove the seedlings from their containers and tease apart the individual leeks. It’s not difficult to separate them because they grow slowly and don’t really have a whole lot of roots to get tangled. Then trim the leaves with scissors to about 3 inches. Some of the seedlings may have one or two extra long, scraggly roots. You can trim those to about 3 inches too.
Then place a two rows of seedlings down in the trench, leaning them up against the walls. The leeks should be spaced about 3 to 4 inches apart in the rows. Then carefully add about an inch of soil back into the hole so that the roots and a bit of the stalks are covered. Pat the soil down all the way around the leeks so that they are standing upright, not leaning against the wall of the trench. Then gently water them.
As the leeks begin to grow, add more soil about an inch at a time so that the stalk remains covered up to just below where the leaves split off. You’ll have to do this every couple of weeks through the growing season. In the fall you have leeks with nice long, tender stalks to harvest.
forgottenpickles.com 
Very helpful post! I haven’t tried growing leeks yet (except a couple of compost-pile rescues, but they’re already grown, they just need reviving), but now I know enough to attempt it next year. Thanks! :)
Good post. I like your trellis that is in the picture the one with the shirt on it. What do you use those trellises for?
Thanks! Right now the the trellises have peas growing along them (though the peas are not quite tall enough to reach them yet.) If all goes according to plan they’ll have tomatoes growing up them when the peas are finished. We’ll be putting up at least one more for cucumbers too.