Before planting it is a good idea to find your USDA Zone info to estimate your garden schedule. 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 Petaluma 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 tend to make it in some cold which tells us that you can plant them a bit earlier in the year than other frost tender plants.

The earliest that you can plant purple coneflower in Petaluma 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 grow to maturity. If you are starting your purple coneflower indoors then you might be able to get away with starting them a couple of weeks earlier.

Last Frost Date

In Petaluma the average date of last frost happens on February 15. You can expect an average low temperature of 25°F in the coldest months of winter.

Since the USDA zone info for Petaluma is just an average the actual date of last frost will vary from year to year. Since half of the time in Petaluma there is a last frost after February 15 be ready to cover your purple coneflower in the event of a surprise late frost.

USDA Zone Info for Petaluma

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 Petaluma

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