Amount of Fertilizer for Sweet Corn

Soil Quality

• Sweet corn requires a soil pH between 5.5 and 7.0 to grow well. A soil test performed before planting indicates the pH and any necessary amendments required to bring the soil bed to the proper level. Soils must also provide excellent drainage and a nutrient-rich organic matter content. Amending the planting site with compost before you plant improves the drainage and moisture retention qualities of your garden while also providing some trace nutrients to the site.

Pre-planting Fertilizers

• Gardens that provide an ample amount of nitrogen encourage the corn to grow healthy, sturdy stalks and large ears. Working a nitrogen-based fertilizer into the planting bed before sowing the corn seed ensures the plants have access to the necessary nitrogen for a healthy start and continued growth. The amount of nitrogen needed depends on what is naturally available in your bed, but an application of 2 lbs. of a 16-16-8 fertilizer or similar to every 100 square feet of corn bed usually suffices.

Starter Fertilizers

• A starter fertilizer provides instant nutrients to seedlings or transplants, which helps encourage the sweet corn to form a healthy root system and quickly establish in the bed. Application of these liquid fertilizers occurs immediately after transplanting or when the seedlings first begin to emerge from the soil. A 9-45-15 fertilizer diluted and applied at the rate recommended on the label provides nutrients to the plants until the roots develop enough to absorb nutrients from the soil.

Side Dressing Corn

• Further fertilization is required once the sweet corn begins to grow and use up the nitrogen supplied at planting. An application of a half-pound of 34-0-0 fertilizer per 100 square feet when the plants are 6 to 10 inches tall and a second application of a quarter-pound of 34-0-0 fertilizer as the stalks begin producing silks at the top replenishes the nutrients in the soil bed. Nitrogen fertilizers applied directly to plant roots can damage the corn, so it's necessary to side dress. Side dressing involves applying the fertilizers six to eight inches away from the base of the plant. Watering after application helps the fertilizer dilute and leach to the corn roots.