Although a leek looks like an overgrown green onion, it is not at all alike in flavor or culinary use. The leek has a very mild flavor and should be cooked before eating. Leeks can stay in the ground in Ohio for one year, even through the winter. To start a leek garden, purchase starter plants at the nursery. The leek is very cold-hardy, but the seedling will need protection from the cold, so plant leeks after all danger of frost has passed.
Choose a location in the garden that gets a full day of sun.
Test the pH of the soil with a soil testing kit, available at garden centers. Aim for a soil pH between 6.2 to 6.8, unless you have muck soil, then the pH should be between 5.4 and 5.6.
Dig up the planting area to a depth of 12 inches. Add a 4-inch layer of compost and mix it into the soil. Add any other amendments required by the soil pH test results.
Plant the leek seedlings 3 to 4 inches apart.
Water frequently to keep the soil moist. Leek plants have very shallow root systems and will get tough if their soil is allowed to dry. Agriculturists at Utah State University suggest giving leek plants 18 inches water of each week.
Sidedress leeks with nitrogen (21-0-0) at 1/2 lb. per 100 square feet when they reach 12 inches in height. To do this, dig a 12-inch deep furrow, 5 to 6 inches from the row of leeks. Scatter the fertilizer into the furrow and cover it with soil.
Check the plants for pests. Leeks in Ohio gardens are prone to onion thrips. Control infestations with neem oil or chemical insecticides such as Diazinon.