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

By checking out the USDA zone info for Ottawa it's a good idea to determine when it's possible to plant liatris.

Planting Calendar for Liatris

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

You can plant liatris a lot earlier in the year because they do well in cold.

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

Last Frost Date

In Ottawa the average date of last frost happens on April 15. It might get as low as -15°F during the coldest months of winter.

Just be sure to remember that USDA zone info for Ottawa is an average and the actual date of last frost is different every year. Half of the time in Ottawa last frost occurs after April 15 so just be sure to be ready to cover your liatris in the event of a surprise late frost.

USDA Zone Info for Ottawa

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 Ottawa

You may be interested in your other planting guides for Ottawa.