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

By reviewing the USDA zone info for Sonora it's a good idea to figure out when it's possible to plant purple coneflower.

Planting Calendar for Purple Coneflower

Frost tolerance for purple coneflower:	Tolerant of a very small amount of frost.
When to plant:	Up to 3 weeks before last frost.

Purple Coneflower can survive in very little cold which tells us that you can plant them just a tiny bit earlier in the year than other frost tender plants.

The earliest that you can plant purple coneflower in Sonora is February. However, you really should wait until March if you don't want to take any chances.

The last month that you can plant purple coneflower and expect a good harvest is probably September. You probably don't want to wait any later than that or else your purple coneflower may not have a chance to fully mature. Starting your purple coneflower indoors is a great way to get them started a couple of weeks earlier.

Last Frost Date

On average the last frost has passed is on February 15 in Sonora. In the coldest months of winter you should expect an average low temperature of 20°F.

It's important to remember that USDA zone info for Sonora is just an average and the actual date of last frost will vary from year to year. Half of the time in Sonora you get a frost after February 15 so make sure that you are prepared to cover your purple coneflower in the event of a surprise 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.