The USDA Zone info is a great tool for gardeners to help us estimate your gardening schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

In Helena you can figure out when it's possible to plant browallia by reviewing the USDA zone info.

Planting Calendar for Browallia

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

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

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

The last month that you can plant browallia and expect a good harvest is probably August. If you wait any later than that and your browallia may not have a chance to fully mature. Starting your browallia indoors is a great way to get them started a couple of weeks earlier.

Last Frost Date

On average the last frost when the weather gets warmer is on March 15 in Helena. It might get as low as 10°F during the coldest months of winter.

Remember that USDA zone info for Helena is an average and the actual date of last frost can change quite a bit from year to year. Half of the time in Helena you get a frost after March 15 so always be ready to protect your browallia if you have a late frost.

USDA Zone Info for Helena

Here is the info for USDA Zone 8a.

Average Date of Last Frost (spring)	March 15
Average Date of First Frost (fall)	November 15
Lowest Expected Low	10°F
Highest Expected Low	15°F

This means that on a really cold year, the coldest it will get is 10°F. On most years you should be prepared to experience lows near 15°F.

Plants to Grow in Helena

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