One of the best tools that you have as gardeners to help us figure out 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 will be able to figure out when you can plant flower-of-an-hour by referring to the USDA zone info for Walla Walla.

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 mild cold which tells us that you can plant them just a tiny bit earlier in the year than plants that are more sensitive to the cold.

The earliest that you can plant flower-of-an-hour in Walla Walla 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. You probably don't want to wait any later than that or else your flower-of-an-hour may not have a chance to really do well. Starting your flower-of-an-hour indoors is a great way to get them started a little bit earlier.

Last Frost Date

The average date of last frost is April 15 in Walla Walla. In the coldest months of winter you should expect an average low temperature of 0°F.

Since the USDA zone info for Walla Walla is an average the actual date of last frost is different every year. Half of the time in Walla Walla last frost occurs after April 15 so be sure to be ready to cover your flower-of-an-hour in the event of a surprise late frost.

USDA Zone Info for Walla Walla

Here is the info for USDA Zone 7a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	0°F
Highest Expected Low	5°F

This means that on a really cold year, the coldest it will get is 0°F. On most years you should be prepared to experience lows near 5°F.

Plants to Grow in Walla Walla

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