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

A way of estimating when it's possible to plant campanula is to use the USDA zone info for Stillwater.

Planting Calendar for Campanula

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

Campanula do well in moderate cold which tells us that you can start planting them earlier than more sensitive plants.

The earliest that you can plant campanula in Stillwater 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. Any later than that and your campanula may not have a chance to really do well. Starting your campanula indoors is a great way to get them started a few weeks earlier.

Last Frost Date

On average the last frost is on May 15 in Stillwater. You should expect an average low temperature of -25°F in the coldest months of winter.

Since the USDA zone info for Stillwater is an average the actual date of last frost will vary from year to year. Since half of the time in Stillwater you get a frost after May 15 be ready to cover your campanula in the event of one of those late frosts.

USDA Zone Info for Stillwater

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 Stillwater

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