The USDA Zone info is a great tool for gardeners to help us figure out 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.

The USDA zone info for Harrisburg can be looked at to figure out when to plant phlox.

Planting Calendar for Phlox

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

Phlox can survive in moderate cold which tells us that you can plant them a little bit earlier in the year than other plants that might not handle the cold.

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. You probably don't want to wait any later than that or else your phlox may not have a chance to really do well. Starting your phlox indoors is a great way to get them started a few weeks earlier.

Last Frost Date

In Harrisburg the average date of last frost happens on April 15. In the coldest months of winter you can expect an average low temperature of 5°F.

Since the USDA zone info for Harrisburg is not always accurate the actual date of last frost will vary from year to year. Half of the time in Harrisburg it frosts late in the year after April 15 so make sure that you are ready to cover your phlox in the event of one of those late frosts.

USDA Zone Info for Harrisburg

Here is the info for USDA Zone 7b.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	5°F
Highest Expected Low	10°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 10°F.

Plants to Grow in Harrisburg

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