Before planting it is a good idea to find your USDA Zone info to estimate 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.

The USDA zone info for San Francisco can be reffered to in order to figure out when it's the best time to plant radishes.

Planting Calendar for Radishes

Frost tolerance for radishes:	Very tolerant of frost.
When to plant:	Up to 7 weeks before last frost.

Radishes tend to make it in a bit of cold which means that you can plant them a lot earlier in the year than more sensitive plants.

The earliest that you can plant radishes 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 radishes and expect a good harvest is probably October. You probably don't want to wait any later than that or else your radishes may not have a chance to fully mature. You can get started a few weeks earlier by starting your radishes indoors.

Last Frost Date

On average the last frost when the weather gets warmer is on January 31 in San Francisco. In the coldest months of winter you can expect an average low temperature of 35°F.

Always keep in mind that USDA zone info for San Francisco may not be accurate from year to year and the actual date of last frost can change quite a bit from year to year. Since half of the time in San Francisco it frosts late in the year after January 31 be ready to cover your radishes 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.