Before planting it is a good idea to find your USDA Zone info to figure out your garden schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

The first opportunity to plant evolvulus in Helena should be estimated by referring to the USDA zone info.

Planting Calendar for Evolvulus

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

It's a bad idea to plant evolvulus 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 evolvulus 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 evolvulus and expect a good harvest is probably August. If you wait any later than that and your evolvulus may not have a chance to really do well. You can get started a few weeks earlier by starting your evolvulus indoors.

Last Frost Date

On average the last frost when the weather gets warmer is on May 15 in Helena. You can expect an average low temperature of -25°F in the coldest months of winter.

It's important to remember that USDA zone info for Helena is just an average and the actual date of last frost changes from year to year. Half of the time in Helena there is a last frost after May 15 so be sure to be ready to protect your evolvulus in the event of 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.