Growing Corn

CornNative to North and South America, corn (or maize) was cultivated some 4,000 years before Columbus first set foot in the New World. Today home gardeners know that the flavor of a fresh picked ear of heirloom corn delivered directly to a pot of boiling water is worth all the effort, fertilizer and space required for growing corn.

Site Preparation:

Corn requires full sun, ample water and deep rich soil to perform well. Prepare the planting site by working in generous amounts of compost. Corn needs to be well protected from frost.

Tip: Cover the growing area with plastic for two to four weeks prior to planting to warm the soil.

How to Plant:

Heirloom CornCorn seed should be planted directly into the soil after it has warmed in the spring (two weeks after your average last-frost date). Sow seeds 1 inch deep, 4-6 inches apart. Plant in blocks or short rows to ensure even pollination. Undeveloped kernels indicate uneven pollination. Plant a new crop every two weeks to ensure harvest throughout the growing season. Corn is a heavy feeder. Fertilize with 1/2 strength high nitrogen fertilizer until tassels develop.

Consider adding kelp meal to organic vegetable gardens. It’s chock-full of micro-nutrients and is especially good for supplying trace minerals to crops that will be consumed. Will also help guard against plant stresses such as insects, frost, disease and drought.

Tip: Make sure that the entire root zone is damp as corn ears mature. Water at the base around stalks. Soaking the leaves rather than the roots washes away pollen, and reduces the number of kernels that develop.


Corn is ready to harvest three weeks after tassels appear. Look for dark green husks, brown, supple silks and plump kernels that squirt “milky” liquid when pinched. Corn tastes best when it is picked in the late afternoon and should be twisted from the plant in a downward motion. Sweet corn requires 65-90 days to reach maturity, depending on the variety.

Insects and Diseases:

Rotate corn with other crops to prevent recurring pest or disease problems. Corn earworm, deer and raccoon are common pests of corn. Discourage animal pests with fencing, repellents and scare devices.

Spinosad is a relatively new biological pesticide that can be used to effectively combat earworms on corn. Mix 4 Tbsp. per gallon of water and treat silk frequently as it grows. Approved for organic use, spinosad does not significantly impact beneficial insects and spiders while controlling pests.

White or grayish swellings are signs of smut. A common fungal disease that should be treated with copper or sulfur fungicides.

Seed Saving Instructions:

All heirloom varieties are wind pollinated and will cross-pollinate with each other. Varieties should be hand-pollinated or isolated by one mile to ensure purity. Allow ears to dry on plants, harvest and shell.

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