One of the best tools that you have as gardeners to help us figure out 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.

By checking out the USDA zone info for Philadelphia it's a good idea to figure out when you can plant phlox.

Planting Calendar for Phlox

Frost tolerance for phlox:	Tolerant of some frost.
When to plant:	Up to 5 weeks before last frost.

Since phlox are moderately cold tolerant you can plant them a bit earlier in the year than plants that are more sensitive to the cold.

The earliest that you can plant phlox in Philadelphia 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 phlox and expect a good harvest is probably September. Any later than that and your phlox may not have a chance to really do well. You can get started a couple of weeks earlier by starting your phlox indoors.

Last Frost Date

On average all chance of frost has passed is on April 15 in Philadelphia. It might get as low as 0°F during the coldest months of winter.

Since the USDA zone info for Philadelphia may not be accurate from year to year the actual date of last frost is different every year. Half of the time in Philadelphia last frost occurs after April 15 so make sure that you are prepared to cover your phlox in the event of a surprise late frost.

USDA Zone Info for Philadelphia

Here is the info for USDA Zone 7a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	0°F
Highest Expected Low	5°F

This means that on a really cold year, the coldest it will get is 0°F. On most years you should be prepared to experience lows near 5°F.

Plants to Grow in Philadelphia

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