One of the best tools that you have as gardeners to help us estimate your gardening schedule is the USDA zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

A common way of making a decision about when it's the best time to plant torenia is to refer to the USDA zone info for Decorah.

Planting Calendar for Torenia

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

Since torenia require warm weather you need to wait until after the last frost before you can plant them.

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

Last Frost Date

The average date of last frost is 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 not always accurate the actual date of last frost is different every year. Half of the time in Decorah you get a frost after May 15 so be sure to be ready to protect your torenia 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.