How to Grow Sweet Corn in Ontario

Sweet corn is a crop which should be planted in larger gardens. Like most vegetables, corn will grow best in areas with plenty of sunlight.

Soil Preparation

Work the top 8-10 inches of soil before planting. Remove weeds, rocks and trash. Work the soil only when it is dry enough not to stick to garden tools.


Use 2-3 pounds of fertilizer such as 10-10-10 for each 100 square feet of garden area. Spread the fertilizer evenly over the soil. Work it into the soil 3-4 inches deep. Rake the soil to smooth the surface.


Silver Queen


Sweet corn is hurt by frost. So plant it when there is no more danger of frosty weather.

If you have room, plant again when the first corn plants have 3-5 leaves. This usually takes 2-3 weeks.

You will need 1-2 ounces of seed for every 100 feet of row. Do not use seed saved from last year’s sweet corn. The seeds will not grow a good crop.

Sweet corn grows best when planted in several short rows instead of one long row. This makes it easier for the corn plants to pollinate. Good pollination will help your ears of corn have plump, juicy kernels.

Plant the corn seeds about 1 inch deep and 3-4 inches apart in the row. Space the rows 2 1/2-3 feet apart. After the plants are up, thin them to one foot apart. If you plant them closer, your corn will have small, poorly-filled ears. See figures 1 and 2.


Water corn as needed to keep it from wilting. Do not let corn suffer from lack of water when the kernels are forming.

Care During the Season

Hoe or till the soil just under the surface. Hoe the weeds off just below the soil’s surface. Do not hurt the corn roots which are close to the top of the soil.

When the plants are about 2 feet tall, apply 1 cup of fertilizer for each 10 feet of garden row. Scatter the fertilizer evenly between the rows. Mix it lightly with the soil. Water after fertilizing. See figure 3.

Insect Pests

Sweet corn has few problems. But the most common is the corn earworm. If you notice that your corn has worms in or on the ears, ask your county Extension agent what to use to control this pest. Follow the directions on the container.


The best time to pick corn is in the early morning or evening when it is cool. Juice from the kernels should be milky white and soft.

The silk on the ears should have turned dark brown. The ears should be firm. Kernels on the tips of the unhusked ears should be plump and milky.

Sweet corn is not ready when the juice of the kernel is watery. It is overripe when the kernels get large, chewy and pasty like dough.

To harvest the ears, hold the stalk below the ear. Twist the tip of the ear toward the ground until it breaks off. Cook the corn right away, or store it in the refrigerator until mealtime.

Watch the corn closely because the quality changes fast. Corn is ready about 3 weeks after the tassel grows on top of the corn plant.


Corn has small amounts of many vitamins and minerals.

Corn-on-the-cob is best when it is picked fresh. Cook fresh, sweet corn on the cob or cut is off the cob.

Remove husks, silk and bad spots just before cooking.

Corn which is past its best quality is still good as cream-style corn.


Store corn in the husk. Place it uncovered in the refrigerator for 1-2 days. Corn which is stored more than 2 days loses its sweetness.