Leeks are easy to grow. They require little to no attention and are generally pest-free. In the kitchen, they can be substituted for onions and, unlike onions, can be chopped and frozen for use in the winter after you run out of your own onions.
Home-grown leeks are far superior to those bought in shops and versatile in the kitchen. They are easy to grow from seed, and if you sow at intervals from February to June, you can harvest them from late August, through winter until the following February.
Like most other vegetables, you will get a heavier crop if you grow leeks in a bright position, with soil that has been improved by the addition of plenty of organic matter.
Prepare the soil for leeks by lightening it up with lots of compost. There's no need for much fertilizer. Grocery store leeks have long white stems because the stems have been buried in soil or sand to prevent light from turning them green. You can do this, too. The reward is longer, more useable stems.
To blanch leeks, plant each seedling at the bottom of a hole that's about 6" deep. Fill in around the base of the leek as it gradually gets taller. By the end of the season, the bottom of each plant will have a 6-8" section that's tender and white.
Like onions, leeks started indoors need to be planted early: 10 to 12 weeks before the last frost date. You can sow the seeds closely together in an open flat. To encourage the plants to develop strong roots and a stocky stature, use scissors to give them weekly haircuts. Cutting off all but the bottom 2" of the plant will help force the plant's energy back into the roots. Leeks can be planted outdoors about the time of the last spring frost, though they will survive light frosts even when young — and heavy frosts in the fall.
The closer together you plant leeks, the smaller they will be. Commercial growers usually place them about 6-8" apart and don't thin them. A good technique for home gardeners is to plant them just 2-3" apart, and achieve proper spacing by harvesting baby leeks as you need them. These young leeks are a good substitute for onions in the early summer kitchen.
It is good to rotate the location of your leeks from year to year, avoiding places where onions or garlic have grown, as the same pests and diseases can affect your leeks.