The USDA Zone info is a great tool for gardeners to help us estimate your gardening schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

It's possible to estimate when it's a good idea to plant bidens by referring to the USDA zone info for Swarthmore.

Planting Calendar for Bidens

Frost tolerance for bidens:	Not tolerant of frost.
When to plant:	After all chance of frost has passed.

Since bidens require warm weather it is important to wait until after the last frost when the weather gets warmer before you can plant them.

The earliest that you can plant bidens 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 bidens and expect a good harvest is probably August. You probably don't want to wait any later than that or else your bidens may not have a chance to grow to maturity. You can get started a few weeks earlier by starting your bidens indoors.

Last Frost Date

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

Keep in mind that the actual date of last frost may not be accurate from year to year because it is based on the USDA zone info for Swarthmore and it is different every year. Half of the time in Swarthmore there is a last frost after April 15 so make sure that you are prepared to cover your bidens 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.