The USDA Zone info is a great tool for gardeners to help us determine your gardening schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

You should be able to determine when you can plant lithospermum by checking out the USDA zone info for Ontario.

Planting Calendar for Lithospermum

Frost tolerance for lithospermum:	Not tolerant of frost.
When to plant:	After the last frost has passed.

You can not plant lithospermum until after the last frost has passed because they require warm weather.

The earliest that you can plant lithospermum 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 lithospermum and expect a good harvest is probably August. If you wait any later than that and your lithospermum may not have a chance to grow to maturity. You can get started a little bit earlier by starting your lithospermum indoors.

Last Frost Date

On average the last frost is on April 15 in Ontario. You should expect an average low temperature of -5°F in the coldest months of winter.

Keep in mind that USDA zone info for Ontario is just an average and the actual date of last frost will vary from year to year. Since half of the time in Ontario there is a last frost after April 15 be ready to cover your lithospermum if you have 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.