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.

By referring to the USDA zone info for Prospect you should be able to determine when it's the best time to plant periwinkles.

Planting Calendar for Periwinkles

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

Since periwinkles require warm weather you really should wait until after the last frost has passed before you can plant them.

The earliest that you can plant periwinkles in Prospect 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. If you wait 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

The average date of last frost is April 15 in Prospect. You should expect an average low temperature of -5°F in the coldest months of winter.

Since the USDA zone info for Prospect is just an average the actual date of last frost can change quite a bit from year to year. Half of the time in Prospect it frosts late in the year after April 15 so just be sure to be ready to protect your periwinkles in the event of one of those late frosts.

USDA Zone Info for Prospect

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 Prospect

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