Before planting it is a good idea to find your USDA Zone info to determine your garden schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

It's a good idea to figure out when you can plant browallia by checking out the USDA zone info for Helena.

Planting Calendar for Browallia

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

Browallia do not do well in cold weather which means that you have to wait until it warms up after the last frost has passed before you can plant them.

The earliest that you can plant browallia 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 browallia and expect a good harvest is probably August. Any later than that and your browallia may not have a chance to grow to maturity. If you are starting your browallia 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 Helena. It might get as low as -25°F during the coldest months of winter.

Since the USDA zone info for Helena may not be accurate from year to year the actual date of last frost changes from year to year. Half of the time in Helena last frost occurs after May 15 so make sure that you are ready to cover your browallia if you have a surprise late frost.

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.