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 reffered to in order to figure out when to plant primula.

Planting Calendar for Primula

Frost tolerance for primula:	Very tolerant of frost.
When to plant:	Up to 7 weeks before last frost.

Primula are one of those plants that can tolerate quite a bit of cold weather which tells us that you can plant them much earlier than plants that are more sensitive to the cold.

The earliest that you can plant primula 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 primula and expect a good harvest is probably September. You probably don't want to wait any later than that or else your primula may not have a chance to grow to maturity. You can get started a few weeks earlier by starting your primula indoors.

Last Frost Date

On average all chance of frost has passed is on April 15 in Harrisburg. You should expect an average low temperature of 5°F in the coldest months of winter.

Remember that USDA zone info for Harrisburg is an average and the actual date of last frost changes 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 primula if you have a late frost.

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.