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.

In Ottawa you can determine when it's possible to plant tomatos by looking at the USDA zone info.

Planting Calendar for Tomatos

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

You should not plant tomatos until after the last frost when the weather gets warmer because they do not do well in cold weather.

The earliest that you can plant tomatos in Ottawa 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 grow to maturity. 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 Ottawa the average date of last frost happens on April 15. In the coldest months of winter you should expect an average low temperature of -10°F.

Always keep in mind that the actual date of last frost is an average because it is based on the USDA zone info for Ottawa and it is different every year. Half of the time in Ottawa you get surprised by a frost after April 15 so make sure that you are prepared to cover your tomatos if you have a late frost.

USDA Zone Info for Ottawa

Here is the info for USDA Zone 6a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-10°F
Highest Expected Low	-5°F

This means that on a really cold year, the coldest it will get is -10°F. On most years you should be prepared to experience lows near -5°F.

Plants to Grow in Ottawa

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