The USDA Zone info is a great tool for gardeners to help us estimate your gardening schedule. 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 to plant nigella by looking at the USDA zone info for Princeton.

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 get them planted much earlier than other frost tender plants.

The earliest that you can plant nigella in Princeton 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 fully mature. You can get started a little bit earlier by starting your nigella indoors.

Last Frost Date

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

Just be sure to remember that USDA zone info for Princeton may not be accurate from year to year and the actual date of last frost will vary from year to year. Half of the time in Princeton it frosts late in the year after April 15 so make sure that you are ready to cover your nigella in the event of a late frost.

USDA Zone Info for Princeton

Here is the info for USDA Zone 5b.

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

This means that on a really cold year, the coldest it will get is -15°F. On most years you should be prepared to experience lows near -10°F.

Plants to Grow in Princeton

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