One of the first steps you take when you are making a decision about 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 Billings should be reffered to in order to estimate when it's a good idea to plant torenia.

Planting Calendar for Torenia

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

It's probably a bad idea to plant torenia until after the last frost because they require warm weather.

The earliest that you can plant torenia in Billings 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. You probably don't want to wait any later than that or else your torenia may not have a chance to fully mature. If you are starting your torenia indoors then you might be able to get away with starting them a couple of weeks earlier.

Last Frost Date

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

Remember that the actual date of last frost is not always accurate because it is based on the USDA zone info for Billings and it will vary from year to year. Half of the time in Billings there is a last frost after May 15 so make sure that you are prepared to cover your torenia if you have a surprise late frost.

USDA Zone Info for Billings

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 Billings

You may be interested in your other planting guides for Billings.