One of the best tools that you have as gardeners to help us determine your gardening schedule is the USDA zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

One way of determining when to plant campanula is to look at the USDA zone info for Billings.

Planting Calendar for Campanula

Frost tolerance for campanula:	Tolerant of some frost.
When to plant:	Up to 5 weeks before last frost.

Since campanula do well in moderate cold you can plant them a little earlier in the year than plants that are more sensitive to the cold.

The earliest that you can plant campanula in Billings is March. However, you really should wait until April if you don't want to take any chances.

The last month that you can plant campanula and expect a good harvest is probably August. You probably don't want to wait any later than that or else your campanula may not have a chance to fully mature. Starting your campanula indoors is a great way to get them started a little bit earlier.

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.

Just be sure to remember that the actual date of last frost is not always accurate because it is based on the USDA zone info for Billings and it is different every year. Since half of the time in Billings you get a frost after May 15 be ready to protect your campanula if you have a late frost.

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.