Before planting it is a good idea to find your USDA Zone info to estimate your garden schedule. 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 possible to plant helianthemum by looking at the USDA zone info.

Planting Calendar for Helianthemum

Frost tolerance for helianthemum:	Tolerant of some frost.
When to plant:	Up to 5 weeks before last frost.

You can plant helianthemum a little bit earlier in the year because they do well in moderate cold.

The earliest that you can plant helianthemum in Iowa City is February. However, you really should wait until March if you don't want to take any chances.

The last month that you can plant helianthemum and expect a good harvest is probably September. Any later than that and your helianthemum may not have a chance to fully mature. You can get started a couple of weeks earlier by starting your helianthemum indoors.

Last Frost Date

In Iowa City the average date of last frost happens on April 15. You should expect an average low temperature of -15°F in the coldest months of winter.

It's important to remember that USDA zone info for Iowa City is not always accurate and the actual date of last frost can change quite a bit from year to year. Since half of the time in Iowa City you get surprised by a frost after April 15 be ready to protect your helianthemum if you have a surprise 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.