Before planting it is a good idea to find your USDA Zone info to figure out 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 referring to the USDA zone info for Sterling it's a good idea to estimate when 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.

Since purple coneflower are barely cold tolerant you can plant them just a tiny bit earlier in the year than other plants that might not handle the cold.

The earliest that you can plant purple coneflower in Sterling is March. However, you really should wait until April 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 August. If you wait any later than that and your purple coneflower may not have a chance to grow to maturity. Starting your purple coneflower indoors is a great way to get them started a few weeks earlier.

Last Frost Date

In Sterling the average date of last frost happens on April 15. It might get as low as -15°F during the coldest months of winter.

Since the USDA zone info for Sterling is just an average the actual date of last frost can change quite a bit from year to year. Since half of the time in Sterling there is a last frost after April 15 be ready to protect your purple coneflower if you have one of those late frosts.

USDA Zone Info for Sterling

Here is the info for USDA Zone 5b.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-15°F
Highest Expected Low	-10°F

This means that on a really cold year, the coldest it will get is -15°F. On most years you should be prepared to experience lows near -10°F.

Plants to Grow in Sterling

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