One of the best tools that you have as gardeners to help us estimate your gardening schedule is the USDA zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

A common way of making a decision about when you can plant nierembergia is to look at the USDA zone info for Iowa 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 all chance of frost has passed because they do not do well in cold weather.

The earliest that you can plant nierembergia in Iowa 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 really do well. Starting your nierembergia indoors is a great way to get them started a few weeks earlier.

Last Frost Date

On average all chance of frost has passed is on April 15 in Iowa City. It might get as low as -15°F during the coldest months of winter.

Always keep in mind that USDA zone info for Iowa City is not always accurate and the actual date of last frost changes from year to year. Since half of the time in Iowa City it frosts late in the year after April 15 be ready to protect your nierembergia in the event of a late frost.

USDA Zone Info for Iowa City

Here is the info for USDA Zone 5b.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-15°F
Highest Expected Low	-10°F

This means that on a really cold year, the coldest it will get is -15°F. On most years you should be prepared to experience lows near -10°F.

Plants to Grow in Iowa City

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