One of the first steps you take when you are estimating your gardening schedule is find your USDA Zone info. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

A common way of estimating when to plant scarlet runner beans is to consult the USDA zone info for San Francisco.

Planting Calendar for Scarlet Runner Beans

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

Since scarlet runner beans do not do well in cold weather it is necessary to wait until after the last frost before you can plant them.

The earliest that you can plant scarlet runner beans 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 scarlet runner beans and expect a good harvest is probably September. You probably don't want to wait any later than that or else your scarlet runner beans may not have a chance to grow to maturity. If you are starting your scarlet runner beans indoors then you might be able to get away with starting them a couple of weeks earlier.

Last Frost Date

On average the last 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.

Remember that USDA zone info for San Francisco is an average and the actual date of last frost will vary from year to year. Since half of the time in San Francisco you get a frost after January 31 be ready to cover your scarlet runner beans 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.