Before planting it is a good idea to find your USDA Zone info to determine 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 making a decision about when it's the best time to plant cardinal flower is to look at the USDA zone info for San Francisco.

Planting Calendar for Cardinal Flower

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

It's probably not a good idea to plant cardinal flower until after the last frost because they are not cold tolerant.

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

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 should expect an average low temperature of 35°F.

Remember that the actual date of last frost is not always accurate because it is based on the USDA zone info for San Francisco and it can change quite a bit from year to year. Since half of the time in San Francisco you get surprised by a frost after January 31 be ready to protect your cardinal flower 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.