The USDA Zone info is a great tool for gardeners to help us estimate 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 River Forest can be looked at to figure out when it's a good idea 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.

You can plant rosemary a lot earlier in the year because they are one of those plants that can tolerate quite a bit of cold weather.

The earliest that you can plant rosemary in River Forest 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 couple of weeks earlier.

Last Frost Date

The average date of last frost is April 15 in River Forest. In the coldest months of winter you can expect an average low temperature of -10°F.

Just be sure to remember that the actual date of last frost is just an average because it is based on the USDA zone info for River Forest and it changes from year to year. Since half of the time in River Forest you get surprised by a frost after April 15 be ready to cover your rosemary in the event of one of those late frosts.

USDA Zone Info for River Forest

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 River Forest

You may be interested in your other planting guides for River Forest.