How to grow sweet corn in a home garden

Sweet corn tastes best right after you pick it. The sugars start turning to starch soon after picking, so the closer you are to the pot, the sweeter it is.

Corn is easy to grow if you give it three things. It needs warm soil, plenty of food, and a block planting so the wind can pollinate it.

When to plant sweet corn

Corn is a warm-season crop. Sow it outdoors after your last spring frost, once the soil is at least 60°F (16°C). Supersweet varieties need warmer soil, about 65°F (18°C). In cold, wet soil, corn seed rots before it sprouts.

In short-season areas, choose early varieties that mature in 65 to 75 days. You can also lay black plastic over the bed for a week before sowing to warm the soil.

Where to plant sweet corn

• Full sun, at least 8 hours a day
• Rich, well-drained soil with lots of compost
• A spot that will not shade your other crops, since corn grows 5 to 7 feet (1.5 to 2 m) tall

Plant in blocks, not long rows

Corn is pollinated by wind. Pollen falls from the tassels at the top of the plant onto the silks below. Each silk connects to one kernel. If a silk gets no pollen, that kernel stays empty.

A single long row lets most of the pollen blow away. A block of at least four short rows side by side keeps the pollen close. That gives you fuller ears.

How to plant sweet corn

1. Work 2 inches (5 cm) of compost into the bed.
2. Sow seeds 1 to 1.5 inches (2.5 to 4 cm) deep.
3. Space seeds 8 to 12 inches (20 to 30 cm) apart.
4. Space rows 30 to 36 inches (75 to 90 cm) apart, in a block of at least four rows.
5. Water well and keep the soil moist until seedlings come up.

Sow a new block every 2 weeks, or plant an early, mid-season, and late variety on the same day. That spreads out your harvest.

Types of sweet corn

Type	What it means	Notes
Standard (su)	Classic sweet corn	Turns starchy fast after picking, eat it the same day
Sugary enhanced (se)	Sweeter and more tender	Holds sweetness a few days longer
Supersweet (sh2)	The sweetest type	Needs warmer soil, keep it apart from other types

Supersweet corn needs to be kept away from other types. If it cross-pollinates with standard or sugary enhanced corn, the kernels turn starchy. Plant it far from other corn, or time it so the two do not tassel at the same time.

Water and feeding

Corn is a heavy feeder, and it needs nitrogen most of all. Side-dress with compost or a nitrogen-rich fertilizer when plants are knee-high, and again when the tassels appear.

Give corn about 1 inch (2.5 cm) of water a week. Water matters most from tasseling until the ears fill out. Dry soil at that stage gives you small ears with missing kernels.

Hill a little soil around the base of the stalks as they grow. This helps hold them up in the wind.

How to tell when sweet corn is ready

Most sweet corn is ready about 18 to 24 days after the silks first appear. Check for these signs:

• The silks are brown and dry.
• The ear feels full and firm to the tip.
• A kernel squirts milky juice when you press it with a fingernail.

Clear juice means the corn needs a few more days. Thick, pasty juice means you waited too long.

To pick an ear, hold the stalk and pull the ear down and twist. Pick in the morning when it is cool, and cook it as soon as you can.

Common sweet corn problems

Problem	Likely cause	Fix
Ears with missing kernels	Poor pollination	Plant in blocks, water during tasseling
Caterpillar at the tip of the ear	Corn earworm	Cut off the damaged tip, the rest is fine to eat
Large gray galls on ears or stalks	Corn smut, a fungus	Cut off and trash the galls before they burst
Eaten ears and broken stalks	Raccoons	Fence the patch or pick as soon as ears are ready
Ragged silks and kernels	Earwigs	Here is how to get rid of earwigs

Corn, beans, and squash

Corn, beans, and squash are a classic planting called the Three Sisters. The corn gives pole beans something to climb. The squash leaves shade the soil and hold in moisture.

• How to grow green beans
• How to grow winter squash
• How to grow pumpkins