One of the best tools that you have as gardeners to help us figure out your gardening schedule is the USDA zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

You can estimate when it's possible to plant saxifraga in Philadelphia by referring to the USDA zone info.

Planting Calendar for Saxifraga

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

Since saxifraga do ok in moderate cold you can plant them a bit earlier in the year than other plants that might not handle the cold.

The earliest that you can plant saxifraga 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 saxifraga and expect a good harvest is probably August. Any later than that and your saxifraga may not have a chance to fully mature. If you are starting your saxifraga indoors then you might be able to get away with starting them a couple of weeks earlier.

Last Frost Date

In Philadelphia the average date of last frost happens on April 15. It might get as low as 0°F during the coldest months of winter.

Since the USDA zone info for Philadelphia is just an average the actual date of last frost changes from year to year. Since half of the time in Philadelphia you get surprised by a frost after April 15 be ready to protect your saxifraga if you have one of those late frosts.

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.