Before planting it is a good idea to find your USDA Zone info to figure out your garden schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

The first chance to plant watermelon in Ontario can be determined by reviewing the USDA zone info.

Planting Calendar for Watermelon

Frost tolerance for watermelon:	Not tolerant of frost.
When to plant:	After the last frost has passed.

Watermelon do not do well in cold weather which means that you have to wait until it warms up after the last frost before you can plant them.

The earliest that you can plant watermelon in Ontario is April. However, you really should wait until May if you don't want to take any chances.

The last month that you can plant watermelon and expect a good harvest is probably August. If you wait any later than that and your watermelon may not have a chance to fully mature. You can get started a couple of weeks earlier by starting your watermelon indoors.

Last Frost Date

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

Since the USDA zone info for Ontario is not always accurate the actual date of last frost changes from year to year. Since half of the time in Ontario you get surprised by a frost after April 15 be ready to cover your watermelon in the event of a surprise late frost.

USDA Zone Info for Ontario

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 Ontario

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