Fall Planting Dates for Leeks in Louisiana

Leek Seeds

• Louisiana gardeners can make a fall planting of leek seeds anytime from September 15 through October 15. To soften up the seed’s tough outer coat for better germination results, soak the seeds overnight before planting them. Setting seeds in the soil, space them 3 to 6 inches apart, in rows 6 to 8 inches apart. Sprinkle 1/4 inch of compost or topsoil over the seeds, firming it down to create good soil-to-seed contact. Maintain an even soil moisture during germination and when the seedlings are at least 2 inches tall, thin them to every 6 to 8 inches. Each month, tuck a 1-inch layer of compost around plants and mulch regularly with straw, grass or wood chips. By creating hills up around the stems monthly with compost and mulch, you encourage the growth of longer, thicker white stems.

Leek Sets

• Leek sets -- slender seedlings available from nurseries -- do best if planted from October 1 through November 30. Pencil-thick transplants are your best choice for a fall planting in Louisiana -- they are big enough to handle transplant shock and sturdy enough to make it through the winter. Dig a trench 6 inches deep, planting the seedlings 6 inches apart in the bottom of the trench. Cover them with 1 inch of soil. As the leeks grow, tuck more soil or compost around them until you match the surrounding soil level and the trench is completely filled. This blanches the stems, keeping them white and tender. Provide a monthly feeding of fish emulsion using a 1-to-4 ratio of emulsion to water.

Soil Preparation

• Whether the garden was planted with crops over the summer, or you are putting seeds in it for the first time, prepare the soil before planting. To provide the drainage leeks prefer and the deep, loose environment that encourages good root development, till or spade the soil to a depth of 12 to 15 inches. A raised bed or mounded soil works best. When sowing leek seeds, amend the soil with 1 pound of 8-24-24 fertilizer added to each 25-foot row. If you are using leek sets, add 1 pound of 8-8-8 fertilizer to every 20-foot row. Leek sets benefit from an additional sidedressing of 8-8-8 fertilizer every four weeks during active growth periods.

Diseases and Pests

• The long growing season of fall-planted leeks means diseases and pests have more time to bother your crop. Common diseases affecting Louisiana’s leeks include purple blotch, downy mildew and pink root. Purple blotch begins as a small white spot on the foliage that grows larger, changing to purple or black in color. Beginning as small green flecks on the foliage, downy mildew can cause leaves to collapse. Treat both of these diseases with an application of 1 tablespoon of Mancozeb 80 WP or Ridomil MZ-58 added to a gallon of water. Like its name suggests, pink root turns leek roots a distinctive rosy color, stunting the plants. The only antidote to this soil-born pathogen is transplanting leeks to new soil. Thrips are small, tan, flying insects that feed on the plant’s leaves. Spray them with a mixture of 2 teaspoons of Malathion 57 percent EC added to a gallon of water.