One of the first steps you take when you are estimating your gardening schedule is find your USDA Zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

You can estimate when it's a good idea to plant calliopsis in Ontario by using the USDA zone info.

Planting Calendar for Calliopsis

Frost tolerance for calliopsis:	Not tolerant of frost.
When to plant:	After the last frost.

It's probably a bad idea to plant calliopsis until after the last frost has passed because they do not do well in cold weather.

The earliest that you can plant calliopsis 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 calliopsis and expect a good harvest is probably August. Any later than that and your calliopsis may not have a chance to really do well. If you are starting your calliopsis 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 should expect an average low temperature of -15°F in the coldest months of winter.

Always keep in mind that USDA zone info for Ontario is just an average and the actual date of last frost is different every year. Since half of the time in Ontario it frosts late in the year after April 15 be ready to protect your calliopsis 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.