Before planting it is a good idea to find your USDA Zone info to determine your garden schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

By looking at the USDA zone info for Philadelphia it's a good idea to determine when it's the best time to plant pentas.

Planting Calendar for Pentas

Frost tolerance for pentas:	Not tolerant of frost.
When to plant:	After all chance of frost has passed.

It's not a good idea to plant pentas until after the last frost when the weather gets warmer because they do not do well in cold weather.

The earliest that you can plant pentas in Philadelphia is April. However, you really should wait until May if you don't want to take any chances.

The last month that you can plant pentas and expect a good harvest is probably August. You probably don't want to wait any later than that or else your pentas may not have a chance to fully mature. You can get started a little bit earlier by starting your pentas indoors.

Last Frost Date

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

Since the USDA zone info for Philadelphia is not always accurate the actual date of last frost changes from year to year. Half of the time in Philadelphia it frosts late in the year after March 15 so just be sure to be ready to cover your pentas if you have a surprise late frost.

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.