Before planting it is a good idea to find your USDA Zone info to determine your garden schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

A way of determining when to plant nierembergia is to refer to the USDA zone info for Riverdale.

Planting Calendar for Nierembergia

Frost tolerance for nierembergia:	Not tolerant of frost.
When to plant:	After the last frost when the weather gets warmer.

Nierembergia require warm weather which means that you really should wait until it warms up after all chance of frost has passed before you can plant them.

The earliest that you can plant nierembergia in Riverdale 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 really do well. If you are starting your nierembergia indoors then you might be able to get away with starting them a little bit earlier.

Last Frost Date

In Riverdale the average date of last frost happens on March 15. You can expect an average low temperature of 10°F in the coldest months of winter.

Since the USDA zone info for Riverdale is not always accurate the actual date of last frost changes from year to year. Since half of the time in Riverdale there is a last frost after March 15 be ready to cover your nierembergia if you have a late frost.

USDA Zone Info for Riverdale

Here is the info for USDA Zone 8a.

Average Date of Last Frost (spring)	March 15
Average Date of First Frost (fall)	November 15
Lowest Expected Low	10°F
Highest Expected Low	15°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 15°F.

Plants to Grow in Riverdale

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