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.

You can determine when you can plant flower-of-an-hour in Rock Springs by looking at the USDA zone info.

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.

Since flower-of-an-hour do ok in moderate cold you can plant them slightly earlier in the year than plants that are more sensitive to the cold.

The earliest that you can plant flower-of-an-hour in Rock Springs is March. However, you really should wait until April 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 fully mature. Starting your flower-of-an-hour indoors is a great way to get them started a couple of weeks earlier.

Last Frost Date

In Rock Springs the average date of last frost happens on April 15. You should expect an average low temperature of -20°F in the coldest months of winter.

Remember that USDA zone info for Rock Springs is just an average and the actual date of last frost can change quite a bit from year to year. Half of the time in Rock Springs last frost occurs after April 15 so be sure to be ready to cover your flower-of-an-hour if you have one of those late frosts.

USDA Zone Info for Rock Springs

Here is the info for USDA Zone 5a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-20°F
Highest Expected Low	-15°F

This means that on a really cold year, the coldest it will get is -20°F. On most years you should be prepared to experience lows near -15°F.

Plants to Grow in Rock Springs

You may be interested in your other planting guides for Rock Springs.