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.

The USDA zone info for Lisle should be looked at 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 tend to make it in pretty solid cold which means that you can plant them quite a bit earlier in the year than other plants that might not handle the cold.

The earliest that you can plant rosemary in Lisle 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. Any later than that and your rosemary may not have a chance to really do well. Starting your rosemary indoors is a great way to get them started a few weeks earlier.

Last Frost Date

On average the last frost is on April 15 in Lisle. You can expect an average low temperature of -15°F in the coldest months of winter.

Always keep in mind that USDA zone info for Lisle is an average and the actual date of last frost is different every year. Since half of the time in Lisle it frosts late in the year after April 15 be ready to protect your rosemary if you have a surprise late frost.

USDA Zone Info for Lisle

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 Lisle

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