One of the best tools that you have as gardeners to help us figure out your gardening schedule is the 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.

In Houston you can determine when you can plant nigella 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.

You can plant nigella earlier in the year because they do well in cold.

The earliest that you can plant nigella in Houston 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. If you wait any later than that and 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 few weeks earlier.

Last Frost Date

In Houston the average date of last frost happens on February 15. You can expect an average low temperature of 20°F in the coldest months of winter.

It's important to remember that the actual date of last frost is not always accurate because it is based on the USDA zone info for Houston and it can change quite a bit from year to year. Since half of the time in Houston you get a frost after February 15 be ready to cover your nigella in the event of one of those late frosts.

USDA Zone Info for Houston

Here is the info for USDA Zone 9a.

Average Date of Last Frost (spring)	February 15
Average Date of First Frost (fall)	December 15
Lowest Expected Low	20°F
Highest Expected Low	25°F

This means that on a really cold year, the coldest it will get is 20°F. On most years you should be prepared to experience lows near 25°F.

Plants to Grow in Houston

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