Before planting it is a good idea to find your USDA Zone info to estimate 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 to plant heliotrope in Philadelphia by referring to the USDA zone info.

Planting Calendar for Heliotrope

Frost tolerance for heliotrope:	Not tolerant of frost.
When to plant:	After the last frost.

It's probably not a good idea to plant heliotrope until after the last frost has passed because they require warm weather.

The earliest that you can plant heliotrope 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 heliotrope and expect a good harvest is probably August. Any later than that and your heliotrope may not have a chance to fully mature. You can get started a couple of weeks earlier by starting your heliotrope indoors.

Last Frost Date

In Philadelphia the average date of last frost happens on April 15. You can expect an average low temperature of 0°F in the coldest months of winter.

Just be sure to remember that USDA zone info for Philadelphia may not be accurate from year to year and the actual date of last frost will vary from year to year. Since half of the time in Philadelphia there is a last frost after April 15 be ready to protect your heliotrope in the event of 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.