The USDA Zone info is a great tool for gardeners to help us estimate your gardening schedule. 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 Decorah can be read to determine when to plant thyme.

Planting Calendar for Thyme

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

You can plant thyme quite a bit earlier in the year because they are very cold tolerant.

The earliest that you can plant thyme 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 thyme and expect a good harvest is probably August. If you wait any later than that and your thyme may not have a chance to grow to maturity. If you are starting your thyme 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. In the coldest months of winter you can expect an average low temperature of -25°F.

It's important to remember that the actual date of last frost is an average because it is based on the USDA zone info for Decorah and it can change quite a bit from year to year. Half of the time in Decorah you get surprised by a frost after May 15 so be sure to be ready to cover your thyme 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.