One of the best tools that you have as gardeners to help us figure out 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 way of estimating when to plant periwinkles is to consult the USDA zone info for Pittsburgh.

Planting Calendar for Periwinkles

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

It's a bad idea to plant periwinkles until after the last frost when the weather gets warmer because they are not cold tolerant.

The earliest that you can plant periwinkles in Pittsburgh 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. If you are starting your periwinkles indoors then you might be able to get away with starting them a couple of weeks earlier.

Last Frost Date

In Pittsburgh the average date of last frost happens on April 15. In the coldest months of winter you can expect an average low temperature of -5°F.

Always keep in mind that the actual date of last frost is just an average because it is based on the USDA zone info for Pittsburgh and it changes from year to year. Half of the time in Pittsburgh last frost occurs after April 15 so always be ready to protect your periwinkles in the event of one of those late frosts.

USDA Zone Info for Pittsburgh

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 Pittsburgh

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