One of the first steps you take when you are estimating your gardening schedule is find your USDA Zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

A way of determining when it's a good idea to plant four o' clock is to consult the USDA zone info for Harrisburg.

Planting Calendar for Four O' Clock

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

Since four o' clock require warm weather you need to wait until after all chance of frost has passed before you can plant them.

The earliest that you can plant four o' clock 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 and expect a good harvest is probably August. If you wait any later than that and your four o' clock may not have a chance to grow to maturity. If you are starting your four o' clock indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

In Harrisburg the average date of last frost happens on April 15. It might get as low as 0°F during the coldest months of winter.

Remember that USDA zone info for Harrisburg is an average and 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 prepared to cover your four o' clock if you have one of those late frosts.

USDA Zone Info for Harrisburg

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 Harrisburg

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