Before planting it is a good idea to find your USDA Zone info to figure out your garden schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

A common way of getting a good idea when it's the best time to plant bidens is to look at the USDA zone info for San Francisco.

Planting Calendar for Bidens

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

Bidens are not cold tolerant which tells us that it is necessary to wait until it warms up after the last frost has passed before you can plant them.

The earliest that you can plant bidens 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 bidens and expect a good harvest is probably September. You probably don't want to wait any later than that or else your bidens may not have a chance to really do well. You can get started a few weeks earlier by starting your bidens 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.

Since the USDA zone info for San Francisco is not always accurate the actual date of last frost changes from year to year. Since half of the time in San Francisco there is a last frost after January 31 be ready to protect your bidens in the event of one of those late frosts.

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.