One of the first steps you take when you are estimating your gardening schedule is find your USDA Zone info. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

A way of making a decision about when you can plant nigella is to use the USDA zone info for Havre.

Planting Calendar for Nigella

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

Since nigella do well in cold you can plant them earlier in the year than plants that are more sensitive to the cold.

The earliest that you can plant nigella in Havre is March. However, you really should wait until April if you don't want to take any chances.

The last month that you can plant nigella and expect a good harvest is probably August. Any later than that and your nigella may not have a chance to fully mature. 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

On average the last frost is on May 15 in Havre. You should expect an average low temperature of -30°F in the coldest months of winter.

Keep in mind that USDA zone info for Havre is just an average and the actual date of last frost changes from year to year. Since half of the time in Havre there is a last frost after May 15 be ready to protect your nigella in the event of a surprise late frost.

USDA Zone Info for Havre

Here is the info for USDA Zone 4a.

Average Date of Last Frost (spring)	May 15
Average Date of First Frost (fall)	September 15
Lowest Expected Low	-30°F
Highest Expected Low	-25°F

This means that on a really cold year, the coldest it will get is -30°F. On most years you should be prepared to experience lows near -25°F.

Plants to Grow in Havre

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