Before planting it is a good idea to find your USDA Zone info to figure out your garden schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

You can determine when it's a good idea to plant primula in Philadelphia by checking out the USDA zone info.

Planting Calendar for Primula

Frost tolerance for primula:	Very tolerant of frost.
When to plant:	Up to 7 weeks before last frost.

Primula can survive in cold weather which tells us that you can plant them a lot earlier in the year than other plants that might not handle the cold.

The earliest that you can plant primula 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 primula and expect a good harvest is probably September. If you wait any later than that and your primula may not have a chance to really do well. Starting your primula indoors is a great way to get them started a little bit 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.

Keep in mind that the actual date of last frost is an average because it is based on the USDA zone info for Philadelphia and it will vary from year to year. Half of the time in Philadelphia you get a frost after April 15 so just be sure to be ready to protect your primula if you have 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.