When to Plant Rosemary in Zone 3a

Before planting it is a good idea to find your USDA Zone info to determine your garden schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

A common way of making a decision about when it's the best time to plant rosemary is to refer to the USDA zone info for Zone 3a.


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 much earlier in the year because they are very cold tolerant.

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 3a 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. If you wait any later than that and your rosemary may not have a chance to grow to maturity. 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

On average the last frost is on May 15 in Zone 3a. In the coldest months of winter you can expect an average low temperature of -40°F.

Remember that the actual date of last frost is just an average because it is based on the USDA zone info for Zone 3a and it will vary from year to year. Since half of the time in Zone 3a you get surprised by a frost after May 15 be ready to protect your rosemary if you have a surprise late frost.

USDA Zone Info for Zone 3a

Here is the info for USDA Zone 3a.

Average Date of Last Frost (spring)May 15
Average Date of First Frost (fall)September 15
Lowest Expected Low-40°F
Highest Expected Low-35°F

This means that on a really cold year, the coldest it will get is -40°F. On most years you should be prepared to experience lows near -35°F.

Plants to Grow in Zone 3a

You may be interested in your other planting guides for Zone 3a.