The USDA Zone info is a great tool for gardeners to help us determine your gardening schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

In Iron Mountain you can determine when you can plant rosemary by checking out the USDA zone info.

Planting Calendar for Rosemary

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

Rosemary tend to make it in cold weather which means 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 Iron Mountain 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 really do well. You can get started a couple of weeks earlier by starting your rosemary indoors.

Last Frost Date

On average the last frost has passed is on May 15 in Iron Mountain. It might get as low as -30°F during the coldest months of winter.

Always keep in mind that the actual date of last frost may not be accurate from year to year because it is based on the USDA zone info for Iron Mountain and it is different every year. Half of the time in Iron Mountain it frosts late in the year after May 15 so make sure that you are ready to protect your rosemary if you have a surprise late frost.

USDA Zone Info for Iron Mountain

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 Iron Mountain

You may be interested in your other planting guides for Iron Mountain.