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.

The first chance to plant cardinal flower in Philadelphia can be determined by referring to the USDA zone info.

Planting Calendar for Cardinal Flower

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

Cardinal Flower are not cold tolerant which means that it is important to wait until it warms up after the last frost before you can plant them.

The earliest that you can plant cardinal flower 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 cardinal flower and expect a good harvest is probably August. If you wait any later than that and your cardinal flower may not have a chance to really do well. You can get started a couple of weeks earlier by starting your cardinal flower indoors.

Last Frost Date

On average all chance of frost has passed is on April 15 in Philadelphia. In the coldest months of winter you can expect an average low temperature of 0°F.

Keep in mind that the actual date of last frost is not always accurate 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 there is a last frost after April 15 be ready to cover your cardinal flower in the event of a 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.