Before planting it is a good idea to find your USDA Zone info to figure out your garden schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

In Decorah you can estimate when it's possible to plant black radish by looking at the USDA zone info.

Planting Calendar for Black radish

Frost tolerance for black radish:	Tolerant of some frost.
When to plant:	Up to 5 weeks before last frost.

Black radish can survive in a little bit of cold which tells us that you can plant them just a bit earlier in the year than other frost tender plants.

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

Last Frost Date

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

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