One of the first steps you take when you are determining 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.

The USDA zone info for Santa Rosa can be used to figure out when you can plant asters.

Planting Calendar for Asters

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

Since asters are moderately cold tolerant you can plant them a little bit earlier in the year than plants that are more sensitive to the cold.

The earliest that you can plant asters in Santa Rosa 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 asters and expect a good harvest is probably October. Any later than that and your asters may not have a chance to fully mature. You can get started a few weeks earlier by starting your asters indoors.

Last Frost Date

On average the last frost has passed is on February 15 in Santa Rosa. It might get as low as 25°F during the coldest months of winter.

Since the USDA zone info for Santa Rosa is not always accurate the actual date of last frost can change quite a bit from year to year. Since half of the time in Santa Rosa it frosts late in the year after February 15 be ready to protect your asters if you have one of those late frosts.

USDA Zone Info for Santa Rosa

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 Santa Rosa

You may be interested in your other planting guides for Santa Rosa.