One of the best tools that you have as gardeners to help us estimate your gardening schedule is the USDA zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

The first chance to plant salpiglossis in Philadelphia should be determined by reviewing the USDA zone info.

Planting Calendar for Salpiglossis

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

Since salpiglossis are not cold tolerant it's important to wait until after the last frost has passed before you can plant them.

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

Last Frost Date

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

Keep in mind that USDA zone info for Philadelphia is an average and the actual date of last frost changes from year to year. Since half of the time in Philadelphia you get surprised by a frost after April 15 be ready to protect your salpiglossis 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.