One of the first steps you take when you are getting a good idea your gardening schedule is find your USDA Zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

In San Francisco you can estimate when it's the best time to plant scarlet pimpernels by referring to the USDA zone info.

Planting Calendar for Scarlet Pimpernels

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

Scarlet Pimpernels are barely cold tolerant which means that you can plant them slightly earlier than more sensitive plants.

The earliest that you can plant scarlet pimpernels 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 pimpernels and expect a good harvest is probably September. If you wait any later than that and your scarlet pimpernels may not have a chance to really do well. If you are starting your scarlet pimpernels indoors then you might be able to get away with starting them a couple of weeks earlier.

Last Frost Date

The average date of last frost is January 31 in San Francisco. You should expect an average low temperature of 35°F in the coldest months of winter.

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 is different every year. Half of the time in San Francisco you get surprised by a frost after January 31 so always be ready to protect your scarlet pimpernels if you have 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.