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 figure out when it's a good idea to plant calendula by referring to the USDA zone info.

Planting Calendar for Calendula

Frost tolerance for calendula:	Tolerant of some frost.
When to plant:	Up to 5 weeks before last frost.

Since calendula are moderately cold tolerant you can plant them a little earlier in the year than more sensitive plants.

The earliest that you can plant calendula in Swarthmore 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 calendula and expect a good harvest is probably September. You probably don't want to wait any later than that or else your calendula may not have a chance to fully mature. If you are starting your calendula indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

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

Since the USDA zone info for Swarthmore is not always accurate the actual date of last frost changes from year to year. Half of the time in Swarthmore you get surprised by a frost after April 15 so make sure that you are prepared to cover your calendula in the event of 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.