The Planting Time for Radishes & Turnips in Georgia

Soil Preparation

• The University of Georgia recommends using raised beds for your early spring plantings -- the soil in them warms earlier and drains better than the surrounding low-lying soil. Before the first planting of radishes and turnips in February or September, work a 2- to 4-inch layer of compost into the top 6 to 8 inches of soil using a tiller or shovel. If you have it on hand, also include other organic matter such as leaves or rotted sawdust. In addition to improving fertility, the soil's water-holding capacity gets a nice boost. To reduce evaporation loss from the soil, mulch around seedlings after they emerge, using straw, compost or leaves. Clean plant debris right after harvesting to minimize disease and insect buildup in your soil.

Growing Radishes

• Spring radish planting should typically start in February in Georgia, when the soil has warmed to at least 50 degrees Fahrenheit. Fall planting often begins in September or October, when soil temperatures are around 80 degrees or lower and daytime air temperatures are starting to drop. To measure soil temperature, insert a handheld thermometer into the top 1 to 2 inches of soil. Sow seeds 1/2 inch deep, in 2- to 3-inch-wide bands, allowing roughly 1 inch between seeds and 12 inches between rows. Thin the seedlings when they're around two weeks old. To produce mild and tender radishes, maintain an even soil moisture with regular watering and a 2- to 4-inch layer of mulch. Consider planting gourmet cultivars. Four- to 5-inch long “Shunkyo Semi-Long” radishes have a crisp white flesh, red exterior and a hot and sweet flavor. They mature in 32 days. “Nero Tondo” radishes have a striking black exterior with a spicy flavor, maturing in 50 days.

Growing Turnips

• A relative of the cabbage, globe-shaped turnips have a white or creamy yellow exterior with a crisp and tender interior. They're very cold hardy, and you can sow these seeds in February and March as soon as the soil temperature reaches 45 degrees. Start your fall planting in September or October, once soil temperatures drop below 77 degrees and daytime temperatures are starting to fall. Plant turnip seeds in a 2-inch-wide band, 1/4 to 1/2 inch deep. Space the seeds 1 inch apart, with row spacing set at 12 inches. When seedlings are roughly 2 inches tall, thin them to every 2 to 6 inches. For milder flavored turnips, maintain an even soil moisture through regular watering and deep mulching. “Hakurei” is a white salad turnip with an edible top, and takes 38 days to reach maturity. A traditional southern variety, “Purple Top White Globe” matures in 50 days.

Pests

• To prevent pests and diseases from building up in your soil, rotate the crops. The day you plant, install row covers over your radishes and turnips to protect them from common pests that include aphids, cabbage loopers and root maggots. Aphids are small insects that colonize the undersides of leaves, sucking out the plant's sap and excreting a telltale sticky residue. Cabbage loopers are small green worms, roughly 2 inches long, that munch holes in turnip leaves. You can recognize root maggot flies by their small gray bodies with black abdominal stripes. Smaller than houseflies, they overwinter in soil near roots left in the ground, emerging in the spring to stunt or kill plants by nibbling on their roots.