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.

You can estimate when it's possible to plant nigella in Riverdale by checking out 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 very cold tolerant which tells us that you can plant them much earlier than other plants that might not handle the cold.

The earliest that you can plant nigella in Riverdale 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. You can get started a couple of weeks earlier by starting your nigella indoors.

Last Frost Date

The average date of last frost is April 15 in Riverdale. You should expect an average low temperature of -10°F in the coldest months of winter.

It's important to remember that USDA zone info for Riverdale 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 Riverdale last frost occurs after April 15 so just be sure to be ready to protect your nigella in the event of one of those late frosts.

USDA Zone Info for Riverdale

Here is the info for USDA Zone 6a.

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

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

Plants to Grow in Riverdale

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