Before planting it is a good idea to find your USDA Zone info to figure out 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.

You should be able to determine when it's a good idea to plant nierembergia by using the USDA zone info for Mason City.

Planting Calendar for Nierembergia

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

It's probably not a good idea to plant nierembergia until after the last frost when the weather gets warmer because they require warm weather.

The earliest that you can plant nierembergia in Mason City 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. You probably don't want to wait any later than that or else your nierembergia may not have a chance to grow to maturity. 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

The average date of last frost is April 15 in Mason City. It might get as low as -20°F during the coldest months of winter.

Since the USDA zone info for Mason City is just an average the actual date of last frost will vary from year to year. Since half of the time in Mason City there is a last frost after April 15 be ready to cover your nierembergia in the event of a late frost.

USDA Zone Info for Mason City

Here is the info for USDA Zone 5a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-20°F
Highest Expected Low	-15°F

This means that on a really cold year, the coldest it will get is -20°F. On most years you should be prepared to experience lows near -15°F.

Plants to Grow in Mason City

You may be interested in your other planting guides for Mason City.