One of the first steps you take when you are determining your gardening schedule is find your USDA Zone info. 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 Zone 4b should be looked at to figure out when to plant torenia.

Planting Calendar for Torenia

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

It's not a good idea to plant torenia until after the last frost because they are not cold tolerant.

The earliest that you can plant torenia in Zone 4b 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. If you wait 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 few weeks earlier.

Last Frost Date

On average the last frost has passed is on May 15 in Zone 4b. You should expect an average low temperature of -25°F in the coldest months of winter.

Since the USDA zone info for Zone 4b may not be accurate from year to year the actual date of last frost will vary from year to year. Since half of the time in Zone 4b you get surprised by a frost after May 15 be ready to protect your torenia if you have one of those late frosts.

USDA Zone Info for Zone 4b

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 Zone 4b

You may be interested in your other planting guides for Zone 4b.