The USDA Zone info is a great tool for gardeners to help us figure out your gardening schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

By reviewing the USDA zone info for Philadelphia you should be able to figure out when it's a good idea to plant chrysocephalum.

Planting Calendar for Chrysocephalum

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

Since chrysocephalum require warm weather you must wait until after all chance of frost has passed before you can plant them.

The earliest that you can plant chrysocephalum 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 chrysocephalum and expect a good harvest is probably August. You probably don't want to wait any later than that or else your chrysocephalum may not have a chance to grow to maturity. If you are starting your chrysocephalum indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

On average the last frost when the weather gets warmer is on March 15 in Philadelphia. You should expect an average low temperature of 10°F in the coldest months of winter.

It's important to remember that the actual date of last frost is not always accurate because it is based on the USDA zone info for Philadelphia and it is different every year. Half of the time in Philadelphia you get surprised by a frost after March 15 so be sure to be ready to cover your chrysocephalum in the event of 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.