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.

By reviewing the USDA zone info for Harrisburg you should be able to estimate when it's a good idea to plant four-o-clock flower.

Planting Calendar for Four-o-clock flower

Frost tolerance for four-o-clock flower:	Not tolerant of frost.
When to plant:	After all chance of frost has passed.

Since four-o-clock flower are not cold tolerant you have to wait until after the last frost has passed before you can plant them.

The earliest that you can plant four-o-clock flower in Harrisburg 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 four-o-clock flower and expect a good harvest is probably August. If you wait any later than that and your four-o-clock flower may not have a chance to really do well. If you are starting your four-o-clock flower indoors then you might be able to get away with starting them a little bit earlier.

Last Frost Date

In Harrisburg the average date of last frost happens on April 15. It might get as low as 5°F during the coldest months of winter.

Since the USDA zone info for Harrisburg may not be accurate from year to year the actual date of last frost is different every year. Since half of the time in Harrisburg it frosts late in the year after April 15 be ready to protect your four-o-clock flower 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.