One of the best tools that you have as gardeners to help us estimate 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.

The USDA zone info for Charleston should be looked at to estimate when it's a good idea to plant periwinkles.

Planting Calendar for Periwinkles

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

Since periwinkles are not cold tolerant it's necessary to wait until after all chance of frost has passed before you can plant them.

The earliest that you can plant periwinkles in Charleston 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. You probably don't want to wait any later than that or else your periwinkles may not have a chance to grow to maturity. Starting your periwinkles indoors is a great way to get them started a little bit earlier.

Last Frost Date

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

Just be sure to remember that USDA zone info for Charleston is not always accurate and the actual date of last frost is different every year. Half of the time in Charleston it frosts late in the year after April 15 so always be ready to cover your periwinkles if you have a late frost.

USDA Zone Info for Charleston

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 Charleston

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