One of the best tools that you have as gardeners to help us determine your gardening schedule is the USDA zone info. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

You can estimate when it's possible to plant common hollyhock in Caribou by using the USDA zone info.

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 start planting them earlier than other frost tender plants.

The earliest that you can plant common hollyhock in Caribou 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 common hollyhock and expect a good harvest is probably August. You probably don't want to wait any later than that or else 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 May 15 in Caribou. In the coldest months of winter you should expect an average low temperature of -30°F.

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

USDA Zone Info for Caribou

Here is the info for USDA Zone 4a.

Average Date of Last Frost (spring)	May 15
Average Date of First Frost (fall)	September 15
Lowest Expected Low	-30°F
Highest Expected Low	-25°F

This means that on a really cold year, the coldest it will get is -30°F. On most years you should be prepared to experience lows near -25°F.

Plants to Grow in Caribou

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