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.

A common way of determining when to plant four o' clock is to use the USDA zone info for Swarthmore.

Planting Calendar for Four O' Clock

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

It's a bad idea to plant four o' clock until after the last frost has passed because they do not do well in cold weather.

The earliest that you can plant four o' clock in Swarthmore 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. You probably don't want to wait any later than that or else your four o' clock may not have a chance to really do well. You can get started a couple of weeks earlier by starting your four o' clock indoors.

Last Frost Date

The average date of last frost is April 15 in Swarthmore. In the coldest months of winter you can expect an average low temperature of 0°F.

It's important to remember that USDA zone info for Swarthmore may not be accurate from year to year and the actual date of last frost is different every year. Half of the time in Swarthmore you get a frost after April 15 so make sure that you are prepared to cover your four o' clock if you have a late frost.

USDA Zone Info for Swarthmore

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 Swarthmore

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