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.

The earliest that you can plant dahlia in San Francisco should be figured out by reviewing the USDA zone info.

Planting Calendar for Dahlia

Frost tolerance for dahlia:	Not tolerant of frost.
When to plant:	After all chance of frost has passed.

You really shouldn't plant dahlia until after the last frost has passed because they do not do well in cold weather.

The earliest that you can plant dahlia 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 dahlia and expect a good harvest is probably September. If you wait any later than that and your dahlia may not have a chance to fully mature. You can get started a few weeks earlier by starting your dahlia indoors.

Last Frost Date

In San Francisco the average date of last frost happens on January 31. In the coldest months of winter you should expect an average low temperature of 35°F.

It's important to remember that the actual date of last frost is just an average because it is based on the USDA zone info for San Francisco and it will vary from year to year. Since half of the time in San Francisco you get surprised by a frost after January 31 be ready to protect your dahlia in the event of 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.