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

A way of determining when to plant blue throatwort is to check out the USDA zone info for San Francisco.

Planting Calendar for Blue Throatwort

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

Blue Throatwort are not cold tolerant which tells us that you need to wait until it warms up after the last frost before you can plant them.

The earliest that you can plant blue throatwort 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 blue throatwort and expect a good harvest is probably September. You probably don't want to wait any later than that or else your blue throatwort may not have a chance to grow to maturity. You can get started a little bit earlier by starting your blue throatwort indoors.

Last Frost Date

On average the last frost is on January 31 in San Francisco. It might get as low as 35°F during the coldest months of winter.

Just be sure to 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. Half of the time in San Francisco it frosts late in the year after January 31 so be sure to be ready to cover your blue throatwort 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.