When Do You Plant Radishes in North Carolina?

Types of Radishes

• The strong-flavored radish (Raphanus sativus) belongs in the Brassicaceae family and has some fine company with relatives consisting of broccoli, cabbage, cauliflower, horseradish, mustard, turnips and wasabi. Radish is a root crop enjoyed raw or cooked. Radishes are considered cool-season crops, preferring the early days of spring or the last days of summer for planting. They don’t grow well when planted during summer heat, especially in hot North Carolina summers.

First and Last Frost Dates

• North Carolina’s growing season begins earlier along the coastal plain than in the Piedmont. Average last spring frost dates for the southern coast span March 21 through April 10, the Piedmont spans April 11 to 20 and the mountains vary considerably from April 16 to May 18. First frost dates similarly range from early November along the coast, mid-October on the Piedmont and early to mid-October in the mountains. U.S. Department of Agriculture plant hardiness zones for North Carolina include zones 6a through 8a. Experienced gardeners quickly learn local average last and first frost dates.

General Time Guidelines for Sowing Radishes

• Radishes prefer cool temperatures and early-season growing conditions; they should be harvested before summer's heat. Seeds germinate quickly and seedlings appear six to 10 days after planting. Seed packets advise to plant after the danger of frost, however most gardeners prefer planting first crops one week before the last frost date and every two weeks while the weather remains cool. The days to maturing and when to sow are always printed on the packets.

Radishes for Spring Planting

• The North Carolina Extension Service recommends the following radishes for spring planting: "Cherry Belle," "Early Scarlet Globe," "Champion," "Comet," "Cherry Beauty," "Red Boy" and "Sparkler." Two interesting white radishes to consider are "Hailstone" and "White Icicle." These thin-skinned, fast-growing radishes can be planted continuously through the spring.

Radishes for Early Summer

• If you miss the early spring planting dates but want to try a radish that can take early summer heat, consider the "Rover Hybrid," a fast-growing radish with 21 days to maturity, and "Fire ‘N Ice," a longer-shaped, fast-growing radish with 25 days to maturity. Most radishes growing in summer heat become woody and pithy with strong flavors, but not these two.

Radishes for Fall Planting

• All of the spring radish suggestions can be planted in early fall but pay attention to the days to maturity provided on the packet. Do not plant these later than 28 to 30 days before the average first freeze date for your area, or too early -- avoid planting in the heat.

  Fall radishes, also known as winter varieties, tend to be longer with larger roots. Their growing times are generally twice that of round varieties. If the days to maturity printed on the packet claim 55 to 60 days, plant accordingly based upon the average first freeze date. If you can protect your crop from early frost you can extend the growing season. Winter varieties include "April Cross," "Daikon," "Everest," "Omny," "Long Black Spanish," "Round Black Spanish" and "Watermelon."