Before planting it is a good idea to find your USDA Zone info to determine 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 earliest that you can plant watermelon in Ontario should be figured out by using the USDA zone info.

Planting Calendar for Watermelon

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

It's not a good idea to plant watermelon until after the last frost because they do not do well in cold weather.

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

The last month that you can plant watermelon and expect a good harvest is probably September. You probably don't want to wait any later than that or else your watermelon may not have a chance to grow to maturity. If you are starting your watermelon indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

On average the last frost is on January 31 in Ontario. In the coldest months of winter you can expect an average low temperature of 30°F.

It's important to remember that USDA zone info for Ontario is not always accurate and the actual date of last frost can change quite a bit from year to year. Half of the time in Ontario there is a last frost after January 31 so always be ready to cover your watermelon if you have one of those late frosts.

USDA Zone Info for Ontario

Here is the info for USDA Zone 10a.

Average Date of Last Frost (spring)	January 31
Average Date of First Frost (fall)	December 15
Lowest Expected Low	30°F
Highest Expected Low	35°F

This means that on a really cold year, the coldest it will get is 30°F. On most years you should be prepared to experience lows near 35°F.

Plants to Grow in Ontario

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