Before planting it is a good idea to find your USDA Zone info to determine your garden schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

By referring to the USDA zone info for Philadelphia you will be able to determine when to plant campanula.

Planting Calendar for Campanula

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

Since campanula are one of those plants that can tolerate a little bit of cold weather you can plant them just a bit earlier in the year than more sensitive plants.

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

The last month that you can plant campanula and expect a good harvest is probably September. You probably don't want to wait any later than that or else your campanula may not have a chance to really do well. If you are starting your campanula indoors then you might be able to get away with starting them a little bit earlier.

Last Frost Date

In Philadelphia the average date of last frost happens on March 15. You should expect an average low temperature of 10°F in the coldest months of winter.

It's important to remember that USDA zone info for Philadelphia may not be accurate from year to year and the actual date of last frost can change quite a bit from year to year. Half of the time in Philadelphia last frost occurs after March 15 so make sure that you are ready to protect your campanula in the event of a late frost.

USDA Zone Info for Philadelphia

Here is the info for USDA Zone 8a.

Average Date of Last Frost (spring)	March 15
Average Date of First Frost (fall)	November 15
Lowest Expected Low	10°F
Highest Expected Low	15°F

This means that on a really cold year, the coldest it will get is 10°F. On most years you should be prepared to experience lows near 15°F.

Plants to Grow in Philadelphia

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