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.

In Harrisburg you can figure out when it's possible to plant phlox by checking out the USDA zone info.

Planting Calendar for Phlox

Frost tolerance for phlox:	Tolerant of some frost.
When to plant:	Up to 5 weeks before last frost.

Since phlox do well in moderate cold you can plant them a little earlier in the year than more sensitive plants.

The earliest that you can plant phlox in Harrisburg is February. However, you really should wait until March if you don't want to take any chances.

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

Last Frost Date

The average date of last frost is April 15 in Harrisburg. In the coldest months of winter you should expect an average low temperature of -5°F.

Since the USDA zone info for Harrisburg is an average the actual date of last frost can change quite a bit from year to year. Half of the time in Harrisburg you get surprised by a frost after April 15 so be sure to be ready to cover your phlox in the event of a surprise late frost.

USDA Zone Info for Harrisburg

Here is the info for USDA Zone 6b.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-5°F
Highest Expected Low	0°F

This means that on a really cold year, the coldest it will get is -5°F. On most years you should be prepared to experience lows near 0°F.

Plants to Grow in Harrisburg

You may be interested in your other planting guides for Harrisburg.