Before planting it is a good idea to find your USDA Zone info to determine your garden schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

The earliest that you can plant petunias in Ontario can be determined by checking out the USDA zone info.

Planting Calendar for Petunias

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

Since petunias are barely cold tolerant you can plant them just a tiny bit earlier in the year than more sensitive plants.

The earliest that you can plant petunias in Ontario 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 petunias and expect a good harvest is probably August. Any later than that and your petunias may not have a chance to really do well. You can get started a few weeks earlier by starting your petunias indoors.

Last Frost Date

In Ontario the average date of last frost happens on April 15. You can expect an average low temperature of -5°F in the coldest months of winter.

Keep in mind that USDA zone info for Ontario is an average and the actual date of last frost can change quite a bit from year to year. Half of the time in Ontario last frost occurs after April 15 so be sure to be ready to cover your petunias in the event of a surprise late frost.

USDA Zone Info for Ontario

Here is the info for USDA Zone 6b.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-5°F
Highest Expected Low	0°F

This means that on a really cold year, the coldest it will get is -5°F. On most years you should be prepared to experience lows near 0°F.

Plants to Grow in Ontario

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