One of the first steps you take when you are figuring out your gardening schedule is find your 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.

In Sonora you can determine when it's the best time to plant achillea by reviewing the USDA zone info.

Planting Calendar for Achillea

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

Since achillea do well in cold you can plant them much earlier in the year than plants that are more sensitive to the cold.

The earliest that you can plant achillea 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 achillea and expect a good harvest is probably October. If you wait any later than that and your achillea may not have a chance to grow to maturity. You can get started a few weeks earlier by starting your achillea indoors.

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.

It's important to remember that USDA zone info for Sonora is not always accurate and the actual date of last frost changes from year to year. Half of the time in Sonora you get a frost after February 15 so always be ready to protect your achillea in the event of 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.