One of the best tools that you have as gardeners to help us estimate your gardening schedule is the USDA zone info. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

The USDA zone info for Billings can be reffered to in order to estimate when it's the best time to plant flower-of-an-hour.

Planting Calendar for Flower-of-an-Hour

Frost tolerance for flower-of-an-hour:	Tolerant of a very small amount of frost.
When to plant:	Up to 3 weeks before last frost.

Flower-of-an-Hour do ok in moderate cold which tells us that you can plant them slightly earlier than plants that are more sensitive to the cold.

The earliest that you can plant flower-of-an-hour in Billings 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 flower-of-an-hour and expect a good harvest is probably August. Any later than that and your flower-of-an-hour may not have a chance to grow to maturity. If you are starting your flower-of-an-hour indoors then you might be able to get away with starting them a couple of weeks earlier.

Last Frost Date

In Billings the average date of last frost happens on May 15. You should expect an average low temperature of -25°F in the coldest months of winter.

Remember that USDA zone info for Billings is an average and the actual date of last frost is different every year. Half of the time in Billings you get surprised by a frost after May 15 so always be ready to cover your flower-of-an-hour if you have a surprise late frost.

USDA Zone Info for Billings

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 Billings

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