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.

In Iowa City you can determine when it's a good idea to plant portulaca by reviewing the USDA zone info.

Planting Calendar for Portulaca

Frost tolerance for portulaca:	Not tolerant of frost.
When to plant:	After all chance of frost has passed.

You can not plant portulaca until after the last frost has passed because they are not cold tolerant.

The earliest that you can plant portulaca 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 portulaca and expect a good harvest is probably August. You probably don't want to wait any later than that or else your portulaca may not have a chance to really do well. You can get started a couple of weeks earlier by starting your portulaca indoors.

Last Frost Date

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

Since the USDA zone info for Iowa City is an average the actual date of last frost is different every year. Since half of the time in Iowa City you get surprised by a frost after April 15 be ready to cover your portulaca in the event of 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.