Sweet corn

Growing Guide

Where to plant

Full sun.

Sow depth


Space between seeds / seedlings


Row space


Size of pot needed (width / depth)


Seedling Sow Depth


Best practice

Directly sown

Germination (days)


Maturity (days)


How to Grow

From seed

For early plantings, sow seeds only 1 inch deep; in the hot weather of midsummer, plant them up to 2 inches deep.

The average germination rate for sweet corn is about 75 percent, so plant three seeds together every 7 to 15 inches

Ready to harvest

Three weeks after corn silks appear, start checking ears for peak ripeness.

Pull back part of the husk and pierce a kernel with your thumbnail.

If milky liquid spurts out, the ears are at prime ripeness — rush those ears to the table, refrigerator, or freezer.

Ears on the same stalk usually ripen a few days apart.

Completely dry silk or a yellow or faded-green sheath means the ear is past its prime.

Collect seed

Watch for the seed corn's ear husks to begin to dry and turn brown.

Harvest the ears on the next dry day and before the first frost.

Pull each ear from the plants, pile the ears in a large basket, and carry the basket into your garage or other sheltered areas.

Pull back the husks of each ear to expose the kernels.

Use the husks to braid three or four ears together in a bunch.

Repeat the procedure until all the seed corn is bunched.

Hang the bunches in a room where the air is dry and warm but not too hot.

Air-drying the corn kernels helps to prevent mold.

Check the dried ears three months later for off-color kernels that could indicate bad or cross-pollinated corn.

Remove these kernels and throw them away; if one ear has many off-color kernels, remove and dispose of the entire ear.

Shell the kernels from the remaining ears.

Use one hand to hold an ear over a large bowl and twist off the kernels with your other hand.

Continue twisting until all the kernels have fallen into the bowl.

The kernels will be very wrinkled.

Transfer the kernels into a rodent-proof container.

A large glass jar or metal canister works well.

Store the container in a dry, cool area until planting time, after the ground warms.

When to Grow


Zone 1 - Cool

October , November , December


Zone 2 - Temperate

September , October , November , December


Zone 3 - Subtropical

January , February , July , August , September , October , November , December

Companion Planting

Tips for Care

It is critical to save seeds from many corn plants to maintain genetic diversity in your seed corn and to prevent inbreeding depression, a condition that causes new corn to be short and produce few ears
Although diversity within a corn variety is essential, it is also important to isolate your corn variety from cross-breeding with other varieties.

If neighbors also grow corn, plant your crop as far away as possible from their gardens to prevent pollination by wind.

Alternatively, select corn that pollinates at different times than your neighbors' corn.
Leave ornamental corn and popcorn on the stalks to dry until the first hard frost.

If the weather is cloudy and wet, cut and stack stalks in a cool, dry place until the corn dries.
Corn needs about 1 inch of water a week, particularly when the stalks begin to tassel.

Water stress during pollination will result in ears with lots of missing kernels, so don’t skip watering your corn patch.

Corn can’t compete with weeds, so be sure to kill weeds thoroughly around the stalks for the first month of growth.

Pests & Problems