One of the best tools that you have as gardeners to help us figure out your gardening schedule is the USDA zone info. 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 a good idea to plant peonies is to look at the USDA zone info for Bourbonnais.

Planting Calendar for Peonies

Frost tolerance for peonies:	Tolerant of a very small amount of frost.
When to plant:	Up to 3 weeks before last frost.

Peonies are one of those plants that can tolerate a tiny bit of cold weather which means that you can start planting them slightly earlier than other plants that might not handle the cold.

The earliest that you can plant peonies in Bourbonnais 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 peonies and expect a good harvest is probably August. Any later than that and your peonies may not have a chance to fully mature. If you are starting your peonies indoors then you might be able to get away with starting them a little bit earlier.

Last Frost Date

In Bourbonnais the average date of last frost happens on April 15. You should expect an average low temperature of -15°F in the coldest months of winter.

Since the USDA zone info for Bourbonnais is just an average the actual date of last frost will vary from year to year. Half of the time in Bourbonnais last frost occurs after April 15 so make sure that you are ready to protect your peonies in the event of a surprise late frost.

USDA Zone Info for Bourbonnais

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 Bourbonnais

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