One of the first steps you take when you are determining 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.

The USDA zone info for Great Falls can be used to figure out when it's the best time 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.

Since rosemary do well in cold you can plant them a lot earlier in the year than other frost tender plants.

The earliest that you can plant rosemary in Great Falls 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 really do well. You can get started a little bit earlier by starting your rosemary indoors.

Last Frost Date

On average the last frost when the weather gets warmer is on May 15 in Great Falls. In the coldest months of winter you can expect an average low temperature of -30°F.

Always keep in mind that USDA zone info for Great Falls is an average and the actual date of last frost will vary from year to year. Since half of the time in Great Falls it frosts late in the year after May 15 be ready to protect your rosemary if you have one of those late frosts.

USDA Zone Info for Great Falls

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 Great Falls

You may be interested in your other planting guides for Great Falls.