One of the best tools that you have as gardeners to help us determine 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 estimate when it's possible to plant tall phlox by checking out the USDA zone info for San Francisco.

Planting Calendar for Tall Phlox

Frost tolerance for tall phlox:	Tolerant of some frost.
When to plant:	Up to 5 weeks before last frost.

Tall Phlox tend to make it in some cold which tells us that you can plant them just a bit earlier in the year than other frost tender plants.

The earliest that you can plant tall phlox in San Francisco is January. However, you really should wait until February if you don't want to take any chances.

The last month that you can plant tall phlox and expect a good harvest is probably October. You probably don't want to wait any later than that or else your tall phlox may not have a chance to grow to maturity. Starting your tall phlox indoors is a great way to get them started a little bit earlier.

Last Frost Date

On average the last frost has passed is on January 31 in San Francisco. You should expect an average low temperature of 35°F in the coldest months of winter.

Since the USDA zone info for San Francisco is not always accurate the actual date of last frost will vary from year to year. Half of the time in San Francisco last frost occurs after January 31 so just be sure to be ready to protect your tall phlox if you have a late frost.

USDA Zone Info for San Francisco

Here is the info for USDA Zone 10b.

Average Date of Last Frost (spring)	January 31
Average Date of First Frost (fall)	December 15
Lowest Expected Low	35°F
Highest Expected Low	40°F

This means that on a really cold year, the coldest it will get is 35°F. On most years you should be prepared to experience lows near 40°F.

Plants to Grow in San Francisco

You may be interested in your other planting guides for San Francisco.