Before planting it is a good idea to find your USDA Zone info to estimate your garden schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

One way of getting a good idea when you can plant nierembergia is to consult the USDA zone info for River Falls.

Planting Calendar for Nierembergia

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

Nierembergia are not cold tolerant which means that you have to wait until it warms up after the last frost when the weather gets warmer before you can plant them.

The earliest that you can plant nierembergia in River Falls is May. However, you really should wait until June 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. Any later than that and your nierembergia may not have a chance to fully mature. You can get started a couple of weeks earlier by starting your nierembergia indoors.

Last Frost Date

On average the last frost is on May 15 in River Falls. It might get as low as -25°F during the coldest months of winter.

Remember that the actual date of last frost is not always accurate because it is based on the USDA zone info for River Falls and it changes from year to year. Since half of the time in River Falls it frosts late in the year after May 15 be ready to protect your nierembergia in the event of one of those late frosts.

USDA Zone Info for River Falls

Here is the info for USDA Zone 4b.

Average Date of Last Frost (spring)	May 15
Average Date of First Frost (fall)	September 15
Lowest Expected Low	-25°F
Highest Expected Low	-20°F

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

Plants to Grow in River Falls

You may be interested in your other planting guides for River Falls.