The USDA Zone info is a great tool for gardeners to help us determine your gardening schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

The USDA zone info for Chicago can be read to figure out when to plant rosemary.

Planting Calendar for Rosemary

Frost tolerance for rosemary:	Very tolerant of frost.
When to plant:	Up to 7 weeks before last frost.

Rosemary are very cold tolerant which tells us that you can plant them a quite a bit earlier than plants that are more sensitive to the cold.

The earliest that you can plant rosemary in Chicago 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 rosemary and expect a good harvest is probably September. You probably don't want to wait any later than that or else your rosemary may not have a chance to fully mature. If you are starting your rosemary indoors then you might be able to get away with starting them a little bit earlier.

Last Frost Date

The average date of last frost is April 15 in Chicago. You should expect an average low temperature of -10°F in the coldest months of winter.

Keep in mind that USDA zone info for Chicago may not be accurate from year to year and the actual date of last frost can change quite a bit from year to year. Since half of the time in Chicago you get a frost after April 15 be ready to protect your rosemary if you have a late frost.

USDA Zone Info for Chicago

Here is the info for USDA Zone 6a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-10°F
Highest Expected Low	-5°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 -5°F.

Plants to Grow in Chicago

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