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

In Billings you can estimate when it's a good idea to plant calliopsis by referring to the USDA zone info.

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 all chance of frost has passed because they do not do well in cold weather.

The earliest that you can plant calliopsis in Billings is May. However, you really should wait until June 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. You can get started a little bit earlier by starting your calliopsis indoors.

Last Frost Date

In Billings the average date of last frost happens on May 15. It might get as low as -25°F during the coldest months of winter.

Since the USDA zone info for Billings is an average the actual date of last frost can change quite a bit from year to year. Half of the time in Billings last frost occurs after May 15 so just be sure to be ready to cover your calliopsis in the event of one of those late frosts.

USDA Zone Info for Billings

Here is the info for USDA Zone 4b.

Average Date of Last Frost (spring)	May 15
Average Date of First Frost (fall)	September 15
Lowest Expected Low	-25°F
Highest Expected Low	-20°F

This means that on a really cold year, the coldest it will get is -25°F. On most years you should be prepared to experience lows near -20°F.

Plants to Grow in Billings

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