One of the first steps you take when you are determining your gardening schedule is find your 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 Hillsboro can be used to estimate when it's possible 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 plant them a quite a bit earlier than more sensitive plants.

The earliest that you can plant nigella in Hillsboro 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 really do well. 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 Hillsboro. In the coldest months of winter you can expect an average low temperature of -10°F.

Since the USDA zone info for Hillsboro is just an average the actual date of last frost is different every year. Half of the time in Hillsboro there is a last frost after April 15 so just be sure to be ready to cover your nigella if you have a surprise late frost.

USDA Zone Info for Hillsboro

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 Hillsboro

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