Before planting it is a good idea to find your USDA Zone info to estimate your garden schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

A common way of making a decision about when it's a good idea to plant periwinkles is to refer to the USDA zone info for Downingtown.

Planting Calendar for Periwinkles

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

Since periwinkles are not cold tolerant you must wait until after all chance of frost has passed before you can plant them.

The earliest that you can plant periwinkles in Downingtown 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 periwinkles and expect a good harvest is probably August. Any later than that and your periwinkles may not have a chance to fully mature. Starting your periwinkles indoors is a great way to get them started a little bit earlier.

Last Frost Date

In Downingtown the average date of last frost happens on April 15. It might get as low as -5°F during the coldest months of winter.

Just be sure to remember that USDA zone info for Downingtown is just an average and the actual date of last frost changes from year to year. Half of the time in Downingtown you get surprised by a frost after April 15 so make sure that you are prepared to protect your periwinkles in the event of a surprise late frost.

USDA Zone Info for Downingtown

Here is the info for USDA Zone 6b.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-5°F
Highest Expected Low	0°F

This means that on a really cold year, the coldest it will get is -5°F. On most years you should be prepared to experience lows near 0°F.

Plants to Grow in Downingtown

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