One of the best tools that you have as gardeners to help us figure out your gardening schedule is the USDA zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

A way of making a decision about when it's the best time to plant radicchio is to look at the USDA zone info for Ontario.

Planting Calendar for Radicchio

Frost tolerance for radicchio:	Tolerant of some frost.
When to plant:	Up to 5 weeks before last frost.

Since radicchio are moderately cold tolerant you can plant them a little earlier in the year than more sensitive plants.

The earliest that you can plant radicchio 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 radicchio and expect a good harvest is probably September. Any later than that and your radicchio may not have a chance to really do well. Starting your radicchio indoors is a great way to get them started a little bit earlier.

Last Frost Date

The average date of last frost is April 15 in Ontario. You should expect an average low temperature of -15°F in the coldest months of winter.

Since the USDA zone info for Ontario is not always accurate the actual date of last frost is different every year. Half of the time in Ontario it frosts late in the year after April 15 so make sure that you are ready to protect your radicchio in the event of a surprise 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.