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.

The USDA zone info for Naperville can be reffered to in order to figure out when it's the best time to plant common hollyhock.

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 do well in moderate cold which tells us that you can plant them earlier than plants that are more sensitive to the cold.

The earliest that you can plant common hollyhock in Naperville 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 grow to maturity. Starting your common hollyhock indoors is a great way to get them started a little bit earlier.

Last Frost Date

The average date of last frost is April 15 in Naperville. You should expect an average low temperature of -15°F in the coldest months of winter.

Since the USDA zone info for Naperville is just an average the actual date of last frost changes from year to year. Half of the time in Naperville last frost occurs after April 15 so be sure to be ready to protect your common hollyhock in the event of a late frost.

USDA Zone Info for Naperville

Here is the info for USDA Zone 5b.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-15°F
Highest Expected Low	-10°F

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

Plants to Grow in Naperville

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