One of the first steps you take when you are determining your gardening schedule is find your 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.

By checking out the USDA zone info for Herrin it's possible to estimate when it's a good idea to plant nierembergia.

Planting Calendar for Nierembergia

Frost tolerance for nierembergia:	Not tolerant of frost.
When to plant:	After the last frost has passed.

Since nierembergia are not cold tolerant you have to wait until after the last frost before you can plant them.

The earliest that you can plant nierembergia in Herrin is April. However, you really should wait until May if you don't want to take any chances.

The last month that you can plant nierembergia and expect a good harvest is probably August. If you wait any later than that and your nierembergia may not have a chance to fully mature. If you are starting your nierembergia indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

On average the last frost has passed is on April 15 in Herrin. In the coldest months of winter you can expect an average low temperature of -5°F.

Remember that USDA zone info for Herrin is just an average and the actual date of last frost will vary from year to year. Half of the time in Herrin you get surprised by a frost after April 15 so be sure to be ready to cover your nierembergia if you have one of those late frosts.

USDA Zone Info for Herrin

Here is the info for USDA Zone 6b.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-5°F
Highest Expected Low	0°F

This means that on a really cold year, the coldest it will get is -5°F. On most years you should be prepared to experience lows near 0°F.

Plants to Grow in Herrin

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