One of the best tools that you have as gardeners to help us estimate 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.

In Ottawa you can determine when to plant coreopsis by checking out the USDA zone info.

Planting Calendar for Coreopsis

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

Since coreopsis are moderately cold tolerant you can plant them just a bit earlier in the year than other plants that might not handle the cold.

The earliest that you can plant coreopsis 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 coreopsis and expect a good harvest is probably September. If you wait any later than that and your coreopsis may not have a chance to really do well. If you are starting your coreopsis indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

The average date of last frost is April 15 in Ottawa. You should expect an average low temperature of -10°F in the coldest months of winter.

Since the USDA zone info for Ottawa may not be accurate from year to year the actual date of last frost changes from year to year. Since half of the time in Ottawa you get a frost after April 15 be ready to protect your coreopsis in the event of a surprise late frost.

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.