One of the best tools that you have as gardeners to help us estimate your gardening schedule is the 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 coleus in Helena should be determined by reviewing the USDA zone info.

Planting Calendar for Coleus

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

It's not a good idea to plant coleus until after all chance of frost has passed because they are not cold tolerant.

The earliest that you can plant coleus 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 coleus and expect a good harvest is probably August. If you wait any later than that and your coleus may not have a chance to fully mature. You can get started a little bit earlier by starting your coleus indoors.

Last Frost Date

On average the last frost is on May 15 in Helena. It might get as low as -25°F during the coldest months of winter.

It's important to remember that USDA zone info for Helena is not always accurate and the actual date of last frost changes from year to year. Since half of the time in Helena it frosts late in the year after May 15 be ready to cover your coleus in the event of a 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.