The USDA Zone info is a great tool for gardeners to help us estimate your gardening schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

The earliest that you can plant nigella in Petersburg should be figured out by using the USDA zone info.

Planting Calendar for Nigella

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

Nigella are one of those plants that can tolerate quite a bit of cold weather which means that you can plant them a quite a bit earlier than plants that are more sensitive to the cold.

The earliest that you can plant nigella in Petersburg 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. Any later than that and your nigella may not have a chance to grow to maturity. Starting your nigella indoors is a great way to get them started a little bit earlier.

Last Frost Date

In Petersburg the average date of last frost happens on April 15. In the coldest months of winter you can expect an average low temperature of 5°F.

Always keep in mind that USDA zone info for Petersburg is not always accurate and the actual date of last frost can change quite a bit from year to year. Half of the time in Petersburg it frosts late in the year after April 15 so make sure that you are ready to protect your nigella if you have a surprise late frost.

USDA Zone Info for Petersburg

Here is the info for USDA Zone 7b.

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

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

Plants to Grow in Petersburg

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