Before planting it is a good idea to find your USDA Zone info to estimate 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 should be read to figure out when you can plant napa cabbage.

Planting Calendar for Napa cabbage

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

Napa cabbage do well in cold weather which means that you can plant them much earlier in the year than other plants that might not handle the cold.

The earliest that you can plant napa cabbage 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 napa cabbage and expect a good harvest is probably September. If you wait any later than that and your napa cabbage may not have a chance to fully mature. If you are starting your napa cabbage indoors then you might be able to get away with starting them a couple of weeks 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 just an average the actual date of last frost can change quite a bit from year to year. Half of the time in Ontario it frosts late in the year after April 15 so make sure that you are prepared to cover your napa cabbage if you have a late frost.

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.