One of the best tools that you have as gardeners to help us figure out 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.

The USDA zone info for Iowa City should be looked at to estimate when it's possible to plant nasturtium.

Planting Calendar for Nasturtium

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

It's a bad idea to plant nasturtium until after all chance of frost has passed because they require warm weather.

The earliest that you can plant nasturtium 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 nasturtium and expect a good harvest is probably August. Any later than that and your nasturtium may not have a chance to fully mature. If you are starting your nasturtium 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 Iowa City. You should expect an average low temperature of -15°F in the coldest months of winter.

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. Half of the time in Iowa City you get a frost after April 15 so make sure that you are ready to protect your nasturtium if you have one of those late frosts.

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.