One of the first steps you take when you are getting a good idea your gardening schedule is find your 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.

One way of figuring out when it's a good idea to plant rosemary is to refer to the USDA zone info for Idaho Falls.

Planting Calendar for Rosemary

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

Rosemary do well in quite a bit of cold which tells us that you can plant them quite a bit earlier in the year than other frost tender plants.

The earliest that you can plant rosemary in Idaho Falls 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. You probably don't want to wait any later than that or else your rosemary may not have a chance to fully mature. 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 Idaho Falls. In the coldest months of winter you can expect an average low temperature of -20°F.

Since the USDA zone info for Idaho Falls is not always accurate the actual date of last frost will vary from year to year. Since half of the time in Idaho Falls you get surprised by a frost after April 15 be ready to cover your rosemary in the event of one of those late frosts.

USDA Zone Info for Idaho Falls

Here is the info for USDA Zone 5a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-20°F
Highest Expected Low	-15°F

This means that on a really cold year, the coldest it will get is -20°F. On most years you should be prepared to experience lows near -15°F.

Plants to Grow in Idaho Falls

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