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Sweet corn

Zea mays · Poaceae

Iconic American summer crop, far sweeter when freshly picked

Photo: Silverije, CC BY-SA 3.0, via Wikimedia Commons

Sun: Full sun
Soil: Fertile, well-drained soil with organic matter
Soil pH: 6.0-6.5 is best; 5.8-7.0 is acceptable
Water: At least 1 in per week. Critical at pollination (silking) and while ears fill
Hardiness: Warm-season annual (USDA zones 2-11)
Height and spread: 5-8 ft tall or more x 1-2 ft wide (in-row spacing 12-18 in)

Guv's tipCorn is wind-pollinated, so plant it in blocks of several short rows, not one long line. Harvest when the kernels are milky. Trust me on this one.

Through the year

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

Sow or plant

Harvest

Months are a rough guide. Time it by your own frost dates.

When to plant

Sow direct when the soil reaches about 50-60°F (65°F for extra-sweet or untreated seed): South Carolina coast Mar-mid Apr, South Carolina Piedmont end Mar-May, Minnesota about May

Harvest or flowering

Ears are ready about 20 days after silking, 75-95 days after planting (mid-late summer). Harvest when kernels are milky

Pruning

None. Removing suckers (tillers) is not necessary and may reduce yield

Making more plants

Seed. Plant in blocks of several short rows (corn is wind-pollinated)

Watch out for

Pest

Corn earworm

Look for: Caterpillar and chewed kernels at ear tip

What to do: Plant early-maturing varieties early; Bt; cut off damaged tips

Pest

European corn borer

Look for: Holes in stalks and ears, broken tassels, tunneling

What to do: Bt timed to egg hatch; remove/destroy crop residue after harvest

Disease

Common smut

Ustilago maydis

Look for: Swollen gray-white galls on ears, tassels or stalks that burst into black spores

What to do: Remove galls before they rupture, remove debris, tolerant hybrids

Disease

Common rust

Puccinia sorghi

Look for: Cinnamon-brown powdery pustules on leaves

What to do: Resistant hybrids

Always read and follow the label on any treatment, and check it is approved for use where you live.

Safety and spread

Pets and people: Not toxic. Corn kernels are safe for dogs in moderation, but cobs are a choking and intestinal-blockage hazard. (The ASPCA's "corn plant" is Dracaena, a different plant)

Weed risk: Not on the federal noxious weed list. The USDA PLANTS database shows no federal or state noxious or invasive status

Checked against two or more reputable gardening sources. How we check our facts

Keep it by the back door

The Plant Doctor and the Guv's book

Printable pest and disease charts with real photographs, and all 50 USA plants in one book.

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