One of the best tools that you have as gardeners to help us determine your gardening schedule is the 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.

The USDA zone info for Philadelphia can be used to estimate when it's the best time to plant scarlet pimpernels.

Planting Calendar for Scarlet Pimpernels

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

Scarlet Pimpernels can survive in mild cold which means that you can plant them slightly earlier in the year than other plants that might not handle the cold.

The earliest that you can plant scarlet pimpernels in Philadelphia 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 scarlet pimpernels and expect a good harvest is probably August. You probably don't want to wait any later than that or else your scarlet pimpernels may not have a chance to really do well. You can get started a few weeks earlier by starting your scarlet pimpernels indoors.

Last Frost Date

The average date of last frost is March 15 in Philadelphia. You should expect an average low temperature of 10°F in the coldest months of winter.

Just be sure to remember that USDA zone info for Philadelphia is not always accurate and the actual date of last frost changes from year to year. Half of the time in Philadelphia you get surprised by a frost after March 15 so make sure that you are prepared to protect your scarlet pimpernels in the event of one of those late frosts.

USDA Zone Info for Philadelphia

Here is the info for USDA Zone 8a.

Average Date of Last Frost (spring)	March 15
Average Date of First Frost (fall)	November 15
Lowest Expected Low	10°F
Highest Expected Low	15°F

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

Plants to Grow in Philadelphia

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