The USDA Zone info is a great tool for gardeners to help us determine your gardening schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

In Philadelphia you can estimate when to plant marigold by using the USDA zone info.

Planting Calendar for Marigold

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

It's a bad idea to plant marigold until after the last frost has passed because they are not cold tolerant.

The earliest that you can plant marigold 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 marigold and expect a good harvest is probably August. If you wait any later than that and your marigold may not have a chance to fully mature. Starting your marigold indoors is a great way to get them started a little bit earlier.

Last Frost Date

The average date of last frost is April 15 in Philadelphia. In the coldest months of winter you can expect an average low temperature of 0°F.

Since the USDA zone info for Philadelphia is not always accurate the actual date of last frost is different every year. Since half of the time in Philadelphia it frosts late in the year after April 15 be ready to protect your marigold 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.