Harvest the spring types before average daily temperatures exceed 75 degrees Fahrenheit. Daikon and winter radishes are sown at 2 to 6 inches in a row, depending on root size. These seeding rates require as much as 15 pounds per acre for the spring radishes, and as little as 3 pounds per acre for daikon or winter radishes. Uniform seeding depth is important for uniform maturity. Fertilization Apply according to soil test.
Radishes require high levels of nutrients due to the short growing season and small root system.
Apply Boron at 2 pounds per acre. Irrigation Anything that restricts the rapid growth of radishes results in pithy, cracked, harsh-tasting roots. Ample moisture is the most easily controlled factor in growth. Radishes require 1 inch of water per week. Weed Control Dacthal and Roundup are the only herbicides labeled for use on radishes.