The USDA Zone info is a great tool for gardeners to help us estimate your gardening schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

You can estimate when it's the best time to plant torenia in Helena by looking at the USDA zone info.

Planting Calendar for Torenia

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

Since torenia require warm weather it is important to wait until after the last frost has passed before you can plant them.

The earliest that you can plant torenia in Helena 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. You can get started a couple of weeks earlier by starting your torenia indoors.

Last Frost Date

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

Keep in mind that the actual date of last frost may not be accurate from year to year because it is based on the USDA zone info for Helena and it is different every year. Since half of the time in Helena you get surprised by a frost after May 15 be ready to protect your torenia in the event of one of those late frosts.

USDA Zone Info for Helena

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 Helena

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