One of the first steps you take when you are getting a good idea 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 first opportunity to plant begonias in Helena can be determined by looking at the USDA zone info.

Planting Calendar for Begonias

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

It's not a good idea to plant begonias until after the last frost when the weather gets warmer because they do not do well in cold weather.

The earliest that you can plant begonias 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 begonias and expect a good harvest is probably August. Any later than that and your begonias may not have a chance to grow to maturity. Starting your begonias 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 Helena. You should expect an average low temperature of -25°F in the coldest months of winter.

Just be sure to remember that USDA zone info for Helena is an average and 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 protect your begonias 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.