The USDA Zone info is a great tool for gardeners to help us figure out 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.

The first opportunity to plant flower-of-an-hour in Portola Valley should be determined by reviewing 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.

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 plants that are more sensitive to the cold.

The earliest that you can plant flower-of-an-hour in Portola Valley 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. If you wait any later than that and your flower-of-an-hour may not have a chance to fully mature. You can get started a few weeks earlier by starting your flower-of-an-hour indoors.

Last Frost Date

On average all chance of frost has passed is on January 31 in Portola Valley. In the coldest months of winter you can expect an average low temperature of 30°F.

It's important to remember that the actual date of last frost may not be accurate from year to year because it is based on the USDA zone info for Portola Valley and it is different every year. Half of the time in Portola Valley you get a frost after January 31 so be sure to be ready to protect your flower-of-an-hour if you have one of those late frosts.

USDA Zone Info for Portola Valley

Here is the info for USDA Zone 10a.

Average Date of Last Frost (spring)	January 31
Average Date of First Frost (fall)	December 15
Lowest Expected Low	30°F
Highest Expected Low	35°F

This means that on a really cold year, the coldest it will get is 30°F. On most years you should be prepared to experience lows near 35°F.

Plants to Grow in Portola Valley

You may be interested in your other planting guides for Portola Valley.