Before planting it is a good idea to find your USDA Zone info to figure out your garden schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

You should be able to determine when it's possible to plant petunias by looking at the USDA zone info for Billings.

Planting Calendar for Petunias

Frost tolerance for petunias:	Tolerant of a very small amount of frost.
When to plant:	Up to 3 weeks before last frost.

You can plant petunias a bit earlier in the year because they are barely cold tolerant.

The earliest that you can plant petunias in Billings 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 petunias and expect a good harvest is probably August. You probably don't want to wait any later than that or else your petunias may not have a chance to fully mature. You can get started a little bit earlier by starting your petunias indoors.

Last Frost Date

The average date of last frost is May 15 in Billings. You can expect an average low temperature of -25°F in the coldest months of winter.

It's important to remember that USDA zone info for Billings is just an average and the actual date of last frost will vary from year to year. Half of the time in Billings there is a last frost after May 15 so make sure that you are ready to protect your petunias if you have 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.