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 USDA zone info for Ontario can be reviewed to figure out when you can plant romaine lettuce.

Planting Calendar for Romaine lettuce

Frost tolerance for romaine lettuce:	Very tolerant of frost.
When to plant:	Up to 7 weeks before last frost.

Since romaine lettuce are very cold tolerant you can plant them a lot earlier in the year than other frost tender plants.

The earliest that you can plant romaine lettuce 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 romaine lettuce and expect a good harvest is probably September. If you wait any later than that and your romaine lettuce may not have a chance to fully mature. You can get started a little bit earlier by starting your romaine lettuce indoors.

Last Frost Date

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

Just be sure to remember that the actual date of last frost is an average because it is based on the USDA zone info for Ontario and it can change quite a bit from year to year. Half of the time in Ontario you get surprised by a frost after April 15 so always be ready to protect your romaine lettuce in the event of one of those late frosts.

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.