One of the first steps you take when you are figuring out 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.

In Ontario you can determine when it's the best time to plant tomatos by referring to the USDA zone info.

Planting Calendar for Tomatos

Frost tolerance for tomatos:	Not tolerant of frost.
When to plant:	After the last frost when the weather gets warmer.

You can not plant tomatos until after all chance of frost has passed because they do not do well in cold weather.

The earliest that you can plant tomatos 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 tomatos and expect a good harvest is probably August. You probably don't want to wait any later than that or else your tomatos may not have a chance to fully mature. If you are starting your tomatos indoors then you might be able to get away with starting them a little bit earlier.

Last Frost Date

In Ontario the average date of last frost happens on April 15. You can expect an average low temperature of -15°F in the coldest months of winter.

Since the USDA zone info for Ontario is not always accurate the actual date of last frost is different every year. Since half of the time in Ontario you get surprised by a frost after April 15 be ready to protect your tomatos in the event of one of those late frosts.

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.