The USDA Zone info is a great tool for gardeners to help us estimate your gardening schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

By looking at the USDA zone info for Phoenix it's possible to determine 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 are one of those plants that can tolerate a tiny bit of cold weather which tells us that you can start planting them slightly earlier than other frost tender plants.

The earliest that you can plant flower-of-an-hour in Phoenix is February. However, you really should wait until March 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 September. Any later than that and your flower-of-an-hour may not have a chance to grow to maturity. Starting your flower-of-an-hour indoors is a great way to get them started a couple of weeks earlier.

Last Frost Date

In Phoenix the average date of last frost happens on February 15. In the coldest months of winter you can expect an average low temperature of 25°F.

Remember that USDA zone info for Phoenix is not always accurate and the actual date of last frost changes from year to year. Half of the time in Phoenix there is a last frost after February 15 so just be sure to be ready to cover your flower-of-an-hour if you have a surprise late frost.

USDA Zone Info for Phoenix

Here is the info for USDA Zone 9b.

Average Date of Last Frost (spring)	February 15
Average Date of First Frost (fall)	December 15
Lowest Expected Low	25°F
Highest Expected Low	30°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 30°F.

Plants to Grow in Phoenix

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