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 figuring out when to plant nierembergia is to refer to the USDA zone info for Decorah.

Planting Calendar for Nierembergia

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

It's probably not a good idea to plant nierembergia until after all chance of frost has passed because they require warm weather.

The earliest that you can plant nierembergia in Decorah 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. If you wait any later than that and your nierembergia may not have a chance to fully mature. Starting your nierembergia indoors is a great way to get them started a few weeks earlier.

Last Frost Date

The average date of last frost is May 15 in Decorah. It might get as low as -25°F during the coldest months of winter.

Keep in mind that USDA zone info for Decorah is just an average and the actual date of last frost can change quite a bit from year to year. Since half of the time in Decorah you get surprised by a frost after May 15 be ready to protect your nierembergia if you have one of those late frosts.

USDA Zone Info for Decorah

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 Decorah

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