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

By checking out the USDA zone info for Iowa City it's a good idea to determine when you can plant violas.

Planting Calendar for Violas

Frost tolerance for violas:	Very tolerant of frost.
When to plant:	Up to 7 weeks before last frost.

Violas do well in cold which tells us that you can plant them a quite a bit earlier than other frost tender plants.

The earliest that you can plant violas 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 violas and expect a good harvest is probably September. If you wait any later than that and your violas may not have a chance to grow to maturity. You can get started a few weeks earlier by starting your violas indoors.

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.

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