One of the first steps you take when you are determining your gardening schedule is find your USDA Zone info. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

One way of estimating when it's possible to plant sweet corn is to examine the USDA zone info for Ottawa.

Planting Calendar for Sweet corn

Frost tolerance for sweet corn:	Tolerant of a very small amount of frost.
When to plant:	Up to 3 weeks before last frost.

You can plant sweet corn a bit earlier in the year because they are barely cold tolerant.

The earliest that you can plant sweet corn in Ottawa is March. However, you really should wait until April if you don't want to take any chances.

The last month that you can plant sweet corn and expect a good harvest is probably August. You probably don't want to wait any later than that or else your sweet corn may not have a chance to fully mature. Starting your sweet corn indoors is a great way to get them started a few weeks earlier.

Last Frost Date

On average the last frost is on April 15 in Ottawa. In the coldest months of winter you can expect an average low temperature of -15°F.

Since the USDA zone info for Ottawa may not be accurate from year to year the actual date of last frost changes from year to year. Half of the time in Ottawa you get surprised by a frost after April 15 so always be ready to protect your sweet corn in the event of a surprise late frost.

USDA Zone Info for Ottawa

Here is the info for USDA Zone 5b.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-15°F
Highest Expected Low	-10°F

This means that on a really cold year, the coldest it will get is -15°F. On most years you should be prepared to experience lows near -10°F.

Plants to Grow in Ottawa

You may be interested in your other planting guides for Ottawa.