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.

By using the USDA zone info for San Ramon it's a good idea to determine when it's the best time to plant centaurea.

Planting Calendar for Centaurea

Frost tolerance for centaurea:	Tolerant of some frost.
When to plant:	Up to 5 weeks before last frost.

Since centaurea are moderately cold tolerant you can plant them a little bit earlier in the year than other plants that might not handle the cold.

The earliest that you can plant centaurea in San Ramon 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 centaurea and expect a good harvest is probably October. If you wait any later than that and your centaurea may not have a chance to grow to maturity. If you are starting your centaurea indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

In San Ramon the average date of last frost happens on February 15. It might get as low as 25°F during the coldest months of winter.

Since the USDA zone info for San Ramon may not be accurate from year to year the actual date of last frost changes from year to year. Since half of the time in San Ramon it frosts late in the year after February 15 be ready to cover your centaurea in the event of a surprise late frost.

USDA Zone Info for San Ramon

Here is the info for USDA Zone 9b.

Average Date of Last Frost (spring)	February 15
Average Date of First Frost (fall)	December 15
Lowest Expected Low	25°F
Highest Expected Low	30°F

This means that on a really cold year, the coldest it will get is 25°F. On most years you should be prepared to experience lows near 30°F.

Plants to Grow in San Ramon

You may be interested in your other planting guides for San Ramon.