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.

The USDA zone info for Boulder City can be used to figure out when it's the best time 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 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 plants that might not handle the cold.

The earliest that you can plant nigella in Boulder City is January. However, you really should wait until February if you don't want to take any chances.

The last month that you can plant nigella and expect a good harvest is probably October. You probably don't want to wait any later than that or else 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

On average the last frost when the weather gets warmer is on February 15 in Boulder City. You should expect an average low temperature of 25°F in the coldest months of winter.

Since the USDA zone info for Boulder City is an average the actual date of last frost can change quite a bit from year to year. Since half of the time in Boulder City last frost occurs after February 15 be ready to cover your nigella in the event of a late frost.

USDA Zone Info for Boulder City

Here is the info for USDA Zone 9b.

Average Date of Last Frost (spring)	February 15
Average Date of First Frost (fall)	December 15
Lowest Expected Low	25°F
Highest Expected Low	30°F

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

Plants to Grow in Boulder City

You may be interested in your other planting guides for Boulder City.