One of the first steps you take when you are estimating 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.

It's possible to determine when to plant nierembergia by looking at the USDA zone info for Viroqua.

Planting Calendar for Nierembergia

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

Since nierembergia do not do well in cold weather you have to wait until after the last frost before you can plant them.

The earliest that you can plant nierembergia in Viroqua 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 grow to maturity. You can get started a little bit earlier by starting your nierembergia indoors.

Last Frost Date

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

Since the USDA zone info for Viroqua is not always accurate the actual date of last frost is different every year. Half of the time in Viroqua there is a last frost after May 15 so make sure that you are prepared to cover your nierembergia if you have a late frost.

USDA Zone Info for Viroqua

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 Viroqua

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