One of the best tools that you have as gardeners to help us estimate your gardening schedule is the USDA zone info. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

The USDA zone info for Charleston can be read to determine when it's a good idea to plant polygonums.

Planting Calendar for Polygonums

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

It's probably a bad idea to plant polygonums until after the last frost because they are not cold tolerant.

The earliest that you can plant polygonums in Charleston is March. However, you really should wait until April if you don't want to take any chances.

The last month that you can plant polygonums and expect a good harvest is probably September. You probably don't want to wait any later than that or else your polygonums may not have a chance to really do well. Starting your polygonums indoors is a great way to get them started a few weeks earlier.

Last Frost Date

In Charleston the average date of last frost happens on February 15. In the coldest months of winter you can expect an average low temperature of 20°F.

Since the USDA zone info for Charleston may not be accurate from year to year the actual date of last frost will vary from year to year. Since half of the time in Charleston you get a frost after February 15 be ready to protect your polygonums in the event of a surprise late frost.

USDA Zone Info for Charleston

Here is the info for USDA Zone 9a.

Average Date of Last Frost (spring)	February 15
Average Date of First Frost (fall)	December 15
Lowest Expected Low	20°F
Highest Expected Low	25°F

This means that on a really cold year, the coldest it will get is 20°F. On most years you should be prepared to experience lows near 25°F.

Plants to Grow in Charleston

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