Before planting it is a good idea to find your USDA Zone info to estimate your garden schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

The USDA zone info for Ottawa can be reviewed to determine when it's a good idea to plant nigella.

Planting Calendar for Nigella

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

Nigella can survive in pretty solid cold which tells us that you can plant them quite a bit earlier in the year than other plants that might not handle the cold.

The earliest that you can plant nigella 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 nigella and expect a good harvest is probably September. You probably don't want to wait any later than that or else your nigella may not have a chance to grow to maturity. If you are starting your nigella indoors then you might be able to get away with starting them a little bit earlier.

Last Frost Date

In Ottawa the average date of last frost happens on April 15. You can expect an average low temperature of -10°F in the coldest months of winter.

It's important to remember that USDA zone info for Ottawa may not be accurate from year to year and the actual date of last frost is different every year. Since half of the time in Ottawa you get a frost after April 15 be ready to protect your nigella 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.