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

In Swarthmore you can determine when it's the best time to plant zinnia by referring to the USDA zone info.

Planting Calendar for Zinnia

Frost tolerance for zinnia:	Not tolerant of frost.
When to plant:	After the last frost.

Zinnia are not cold tolerant which means that you must wait until it warms up after the last frost when the weather gets warmer before you can plant them.

The earliest that you can plant zinnia 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 zinnia and expect a good harvest is probably August. Any later than that and your zinnia may not have a chance to grow to maturity. You can get started a little bit earlier by starting your zinnia indoors.

Last Frost Date

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

Just be sure to remember that the actual date of last frost is just an average because it is based on the USDA zone info for Swarthmore and it changes from year to year. Half of the time in Swarthmore it frosts late in the year after April 15 so just be sure to be ready to protect your zinnia in the event of one of those late frosts.

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.