When can I plant Rosemary in Zone 4a

The USDA Zone info is a great tool for gardeners to help us determine our gardening schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for our area.

You can determine when you can plant rosemary in Zone 4a by using the USDA zone info.


Planting Calendar for Rosemary

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

You can plant rosemary much earlier in the year because they do well in cold.

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 Zone 4a 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 rosemary and expect a good harvest is probably August. Any later than that and your rosemary may not have a chance to grow to maturity. Starting your rosemary indoors is a great way to get them started a couple of weeks earlier.

Last Frost Date

The average date of last frost is May 15 in Zone 4a. We can expect an average low temperature of -30°F in the coldest months of winter.

Since the USDA zone info for Zone 4a is just an average our actual date of last frost is different every year. Half of the time in Zone 4a there is a last frost after May 15 so be sure to be ready to cover your rosemary in the event of a surprise late frost.

USDA Zone Info for Zone 4a

Here is the info for USDA Zone 4a.

Average Date of Last Frost (spring)May 15
Average Date of First Frost (fall)September 15
Lowest Expected Low-30°F
Highest Expected Low-25°F

This means that on a really cold year, the coldest it will get is -30°F. On most years you should be prepared to experience lows near -25°F.

Plants to Grow in Zone 4a

You may be interested in our other planting guides for Zone 4a.