When to Plant Rosemary in Lemont, IL

One of the first steps you take when you are making a decision about your gardening schedule is find your USDA Zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

You can determine when it's a good idea to plant rosemary in Lemont by looking at the USDA zone info.

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Planting Calendar for Rosemary

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

Since rosemary are one of those plants that can tolerate quite a bit of cold weather you can plant them much earlier in the year than other frost tender plants.

JanFebMarAprMayJunJulAugSepOctNovDec
Legend 
A good time to plant rosemary
Possibly ok, but a risky time to plant rosemary
Probably not a good time to plant rosemary

The earliest that you can plant rosemary in Lemont 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 grow to maturity. You can get started a few weeks earlier by starting your rosemary indoors.

Last Frost Date

In Lemont the average date of last frost happens on April 15. It might get as low as -15°F during the coldest months of winter.

Since the USDA zone info for Lemont may not be accurate from year to year the actual date of last frost is different every year. Half of the time in Lemont you get surprised by a frost after April 15 so make sure that you are ready to cover your rosemary if you have a late frost.

USDA Zone Info for Lemont

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 Lemont

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