The USDA Zone info is a great tool for gardeners to help us determine 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 trifolium in San Francisco can be determined by referring to the USDA zone info.

Planting Calendar for Trifolium

Frost tolerance for trifolium:	Tolerant of a very small amount of frost.
When to plant:	Up to 3 weeks before last frost.

Trifolium are barely cold tolerant which means that you can plant them slightly earlier than other plants that might not handle the cold.

The earliest that you can plant trifolium 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 trifolium and expect a good harvest is probably September. Any later than that and your trifolium may not have a chance to really do well. You can get started a little bit earlier by starting your trifolium indoors.

Last Frost Date

On average all chance of frost has passed is on January 31 in San Francisco. In the coldest months of winter you can expect an average low temperature of 35°F.

Keep in mind 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 San Francisco and it can change quite a bit from year to year. Half of the time in San Francisco there is a last frost after January 31 so make sure that you are ready to cover your trifolium in the event of 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.