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.

You can estimate when it's the best time to plant scallions in Philadelphia by reviewing the USDA zone info.

Planting Calendar for Scallions

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

Scallions are one of those plants that can tolerate a tiny bit of cold weather which means that you can start planting them slightly earlier than other frost tender plants.

The earliest that you can plant scallions 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 scallions and expect a good harvest is probably August. Any later than that and your scallions may not have a chance to grow to maturity. You can get started a couple of weeks earlier by starting your scallions indoors.

Last Frost Date

In Philadelphia the average date of last frost happens on March 15. It might get as low as 10°F during the coldest months of winter.

It's important to remember that the actual date of last frost is just an average because it is based on the USDA zone info for Philadelphia and it can change quite a bit from year to year. Since half of the time in Philadelphia you get a frost after March 15 be ready to cover your scallions if you have 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.