One of the first steps you take when you are getting a good idea 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.

The earliest that you can plant calliopsis in Prospect Heights should be determined by looking at the USDA zone info.

Planting Calendar for Calliopsis

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

You should not plant calliopsis until after the last frost because they are not cold tolerant.

The earliest that you can plant calliopsis in Prospect Heights 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 fully mature. 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 Prospect Heights. It might get as low as -15°F during the coldest months of winter.

Since the USDA zone info for Prospect Heights is just an average the actual date of last frost will vary from year to year. Half of the time in Prospect Heights you get surprised by a frost after April 15 so make sure that you are prepared to cover your calliopsis in the event of one of those late frosts.

USDA Zone Info for Prospect Heights

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 Prospect Heights

You may be interested in your other planting guides for Prospect Heights.