One of the first steps you take when you are getting a good idea 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.

You should be able to estimate when it's the best time to plant achillea by reviewing the USDA zone info for Santa Rosa.

Planting Calendar for Achillea

Frost tolerance for achillea:	Very tolerant of frost.
When to plant:	Up to 7 weeks before last frost.

Achillea are very cold tolerant which means that you can start planting them much earlier than other frost tender plants.

The earliest that you can plant achillea 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 achillea and expect a good harvest is probably October. Any later than that and your achillea may not have a chance to grow to maturity. Starting your achillea indoors is a great way to get them started a couple of weeks earlier.

Last Frost Date

On average all chance of frost has passed is on February 15 in Santa Rosa. You should expect an average low temperature of 25°F in the coldest months of winter.

Since the USDA zone info for Santa Rosa is just an average the actual date of last frost changes from year to year. Half of the time in Santa Rosa last frost occurs after February 15 so make sure that you are prepared to protect your achillea in the event of a surprise late frost.

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.