The USDA Zone info is a great tool for gardeners to help us determine your gardening schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

You should be able to estimate when to plant calliopsis by looking at the USDA zone info for Ottumwa.

Planting Calendar for Calliopsis

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

It's probably not a good idea to plant calliopsis until after the last frost because they require warm weather.

The earliest that you can plant calliopsis in Ottumwa 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 calliopsis and expect a good harvest is probably August. You probably don't want to wait any later than that or else your calliopsis may not have a chance to really do well. Starting your calliopsis indoors is a great way to get them started a few weeks earlier.

Last Frost Date

The average date of last frost is April 15 in Ottumwa. In the coldest months of winter you should expect an average low temperature of -15°F.

Just be sure to remember that the actual date of last frost is just an average because it is based on the USDA zone info for Ottumwa and it changes from year to year. Half of the time in Ottumwa it frosts late in the year after April 15 so always be ready to protect your calliopsis in the event of one of those late frosts.

USDA Zone Info for Ottumwa

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 Ottumwa

You may be interested in your other planting guides for Ottumwa.