One of the first steps you take when you are estimating your gardening schedule is find your USDA Zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

It's possible to figure out when it's a good idea to plant periwinkles by looking at the USDA zone info for Greencastle.

Planting Calendar for Periwinkles

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

It's a bad idea to plant periwinkles until after the last frost because they require warm weather.

The earliest that you can plant periwinkles in Greencastle 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 grow to maturity. Starting your periwinkles indoors is a great way to get them started a couple of weeks earlier.

Last Frost Date

On average the last frost is on April 15 in Greencastle. In the coldest months of winter you should expect an average low temperature of -15°F.

Keep in mind that USDA zone info for Greencastle is just an average and the actual date of last frost changes from year to year. Half of the time in Greencastle it frosts late in the year 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 Greencastle

Here is the info for USDA Zone 5b.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-15°F
Highest Expected Low	-10°F

This means that on a really cold year, the coldest it will get is -15°F. On most years you should be prepared to experience lows near -10°F.

Plants to Grow in Greencastle

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