Before planting it is a good idea to find your USDA Zone info to estimate your garden schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

By reviewing the USDA zone info for Decorah it's possible to estimate when you can plant alternanthera.

Planting Calendar for Alternanthera

Frost tolerance for alternanthera:	Not tolerant of frost.
When to plant:	After the last frost has passed.

It's not a good idea to plant alternanthera until after the last frost when the weather gets warmer because they are not cold tolerant.

The earliest that you can plant alternanthera in Decorah is May. However, you really should wait until June if you don't want to take any chances.

The last month that you can plant alternanthera and expect a good harvest is probably August. Any later than that and your alternanthera may not have a chance to really do well. Starting your alternanthera indoors is a great way to get them started a few weeks earlier.

Last Frost Date

The average date of last frost is May 15 in Decorah. You should expect an average low temperature of -25°F in the coldest months of winter.

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 it frosts late in the year after May 15 so make sure that you are prepared to cover your alternanthera in the event of a late frost.

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.