Leeks

 Leeks take awhile to mature and like to be started in the fall. These are very cold tolerant vegetables 

 We recommend planting every few weeks from late September thru mid March. You can bareroot transplant these they don't mind they roots being messed with.

Leeks take a long long time to harvest, approximately 8-10 months so don't give up, leeks can be overwintered in zones 3-10 in the U.S. 
For  transplanting, you need to start the seed in raised beds, blanket the seeds ensuring they're covered with 1/4 of an inch of soil. 
After two months they should be ready to be transplanted outdoors, so then you can plant them at least 6 inches apart in any direction.
Leeks are very cold-tolerant.
Example here in Zone 6B for us to harvest Midsummer leeks we need to start seeds in August/September