One of the best tools that you have as gardeners to help us determine 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 earliest that you can plant zinnia in Charleston should be determined by looking at the USDA zone info.

Planting Calendar for Zinnia

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

You can not plant zinnia until after the last frost has passed because they require warm weather.

The earliest that you can plant zinnia 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 zinnia and expect a good harvest is probably August. If you wait any later than that and your zinnia may not have a chance to fully mature. Starting your zinnia indoors is a great way to get them started a few weeks earlier.

Last Frost Date

On average the last frost has passed is on April 15 in Charleston. It might get as low as -10°F during the coldest months of winter.

Since the USDA zone info for Charleston is not always accurate the actual date of last frost will vary from year to year. Since half of the time in Charleston there is a last frost after April 15 be ready to cover your zinnia in the event of one of those late frosts.

USDA Zone Info for Charleston

Here is the info for USDA Zone 6a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-10°F
Highest Expected Low	-5°F

This means that on a really cold year, the coldest it will get is -10°F. On most years you should be prepared to experience lows near -5°F.

Plants to Grow in Charleston

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