One of the best tools that you have as gardeners to help us figure out 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 first opportunity to plant yarrow in Decorah can be figured out by referring to the USDA zone info.

Planting Calendar for Yarrow

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

Yarrow do well in cold which means that you can get them planted much earlier than other frost tender plants.

The earliest that you can plant yarrow 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 yarrow and expect a good harvest is probably August. Any later than that and your yarrow may not have a chance to grow to maturity. Starting your yarrow indoors is a great way to get them started a few weeks earlier.

Last Frost Date

On average all chance of frost has passed is on May 15 in Decorah. In the coldest months of winter you can expect an average low temperature of -25°F.

Since the USDA zone info for Decorah is just an average the actual date of last frost can change quite a bit from year to year. Half of the time in Decorah there is a last frost after May 15 so just be sure to be ready to protect your yarrow 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.