Before planting it is a good idea to find your USDA Zone info to estimate 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.

One way of getting a good idea when it's a good idea to plant common hollyhock is to look at the USDA zone info for Philadelphia.

Planting Calendar for Common hollyhock

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

Common hollyhock are one of those plants that can tolerate a little bit of cold weather which tells us that you can get them planted earlier than more sensitive plants.

The earliest that you can plant common hollyhock 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 common hollyhock and expect a good harvest is probably September. If you wait any later than that and your common hollyhock may not have a chance to really do well. Starting your common hollyhock indoors is a great way to get them started a few weeks earlier.

Last Frost Date

In Philadelphia the average date of last frost happens on April 15. You can expect an average low temperature of 0°F in the coldest months of winter.

Just be sure to remember that the actual date of last frost may not be accurate from year to year because it is based on the USDA zone info for Philadelphia and it is different every year. Half of the time in Philadelphia there is a last frost after April 15 so always be ready to cover your common hollyhock if you have a late frost.

USDA Zone Info for Philadelphia

Here is the info for USDA Zone 7a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	0°F
Highest Expected Low	5°F

This means that on a really cold year, the coldest it will get is 0°F. On most years you should be prepared to experience lows near 5°F.

Plants to Grow in Philadelphia

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