The USDA Zone info is a great tool for gardeners to help us estimate your gardening schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

A common way of determining when it's possible to plant calliopsis is to examine the USDA zone info for Waterloo.

Planting Calendar for Calliopsis

Frost tolerance for calliopsis:	Not tolerant of frost.
When to plant:	After the last frost when the weather gets warmer.

Calliopsis are not cold tolerant which tells us that you must wait until it warms up after the last frost has passed before you can plant them.

The earliest that you can plant calliopsis in Waterloo 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. Any later than that and your calliopsis may not have a chance to grow to maturity. If you are starting your calliopsis indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

In Waterloo the average date of last frost happens on April 15. In the coldest months of winter you should expect an average low temperature of -20°F.

Remember that the actual date of last frost may not be accurate from year to year because it is based on the USDA zone info for Waterloo and it can change quite a bit from year to year. Half of the time in Waterloo you get surprised by a frost after April 15 so make sure that you are ready to cover your calliopsis if you have a late frost.

USDA Zone Info for Waterloo

Here is the info for USDA Zone 5a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-20°F
Highest Expected Low	-15°F

This means that on a really cold year, the coldest it will get is -20°F. On most years you should be prepared to experience lows near -15°F.

Plants to Grow in Waterloo

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