One of the best tools that you have as gardeners to help us estimate your gardening schedule is the 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.

The USDA zone info for Decorah should be used to determine when 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 are one of those plants that can tolerate quite a bit of cold weather you can plant them earlier in the year than other frost tender plants.

The earliest that you can plant rosemary in Decorah 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. If you are starting your rosemary indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

In Decorah the average date of last frost happens on May 15. It might get as low as -25°F during the coldest months of winter.

Just be sure to remember that USDA zone info for Decorah may not be accurate from year to year and the actual date of last frost can change quite a bit from year to year. Since half of the time in Decorah you get a frost after May 15 be ready to cover your rosemary if you have one of those late frosts.

USDA Zone Info for Decorah

Here is the info for USDA Zone 4b.

Average Date of Last Frost (spring)	May 15
Average Date of First Frost (fall)	September 15
Lowest Expected Low	-25°F
Highest Expected Low	-20°F

This means that on a really cold year, the coldest it will get is -25°F. On most years you should be prepared to experience lows near -20°F.

Plants to Grow in Decorah

You may be interested in your other planting guides for Decorah.