One of the best tools that you have as gardeners to help us estimate your gardening schedule is the 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 figuring out when to plant centaurea is to consult the USDA zone info for Sonora.

Planting Calendar for Centaurea

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

Centaurea are moderately cold tolerant which tells us that you can plant them earlier than plants that are more sensitive to the cold.

The earliest that you can plant centaurea in Sonora 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. Any later than that and your centaurea may not have a chance to fully mature. Starting your centaurea indoors is a great way to get them started a little bit earlier.

Last Frost Date

The average date of last frost is February 15 in Sonora. It might get as low as 20°F during the coldest months of winter.

Just be sure to remember that USDA zone info for Sonora is not always accurate and the actual date of last frost is different every year. Half of the time in Sonora it frosts late in the year after February 15 so be sure to be ready to protect your centaurea if you have a late frost.

USDA Zone Info for Sonora

Here is the info for USDA Zone 9a.

Average Date of Last Frost (spring)	February 15
Average Date of First Frost (fall)	December 15
Lowest Expected Low	20°F
Highest Expected Low	25°F

This means that on a really cold year, the coldest it will get is 20°F. On most years you should be prepared to experience lows near 25°F.

Plants to Grow in Sonora

You may be interested in your other planting guides for Sonora.