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.

You should be able to estimate when it's a good idea to plant spearmint by using the USDA zone info for Ottawa.

Planting Calendar for Spearmint

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

Spearmint are one of those plants that can tolerate quite a bit of cold weather which tells us that you can plant them a quite a bit earlier than more sensitive plants.

The earliest that you can plant spearmint 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 spearmint and expect a good harvest is probably September. Any later than that and your spearmint may not have a chance to grow to maturity. If you are starting your spearmint indoors then you might be able to get away with starting them a couple of weeks earlier.

Last Frost Date

The average date of last frost is April 15 in Ottawa. It might get as low as -10°F during the coldest months of winter.

Since the USDA zone info for Ottawa is an average the actual date of last frost will vary from year to year. Half of the time in Ottawa you get surprised by a frost after April 15 so just be sure to be ready to protect your spearmint in the event of one of those late frosts.

USDA Zone Info for Ottawa

Here is the info for USDA Zone 6a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-10°F
Highest Expected Low	-5°F

This means that on a really cold year, the coldest it will get is -10°F. On most years you should be prepared to experience lows near -5°F.

Plants to Grow in Ottawa

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