Before planting it is a good idea to find your USDA Zone info to figure out your garden 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 San Francisco it's possible to determine when to plant alternaria.

Planting Calendar for Alternaria

Frost tolerance for alternaria:	Not tolerant of frost.
When to plant:	After the last frost when the weather gets warmer.

Since alternaria are not cold tolerant it's important to wait until after all chance of frost has passed before you can plant them.

The earliest that you can plant alternaria in San Francisco 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 alternaria and expect a good harvest is probably September. You probably don't want to wait any later than that or else your alternaria may not have a chance to grow to maturity. You can get started a few weeks earlier by starting your alternaria indoors.

Last Frost Date

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

Since the USDA zone info for San Francisco is an average the actual date of last frost is different every year. Half of the time in San Francisco you get a frost after January 31 so always be ready to cover your alternaria if you have a surprise 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.