Plant the radishes. Expect a harvest approximately 22 to 30 days after planting spring varieties, such as Burpee White, Easter Egg, Plum Purple and Snow Belle. Fifty-two to 70 days are needed to bring winter varieties to maturity, such as China Rose, Round Black Spanish or Tama Hybrid. Radishes grow best in loose, well-drained fertile soil and full sun.
Wait for the top of the radish to emerge from the ground. This indicates it is near harvest time.
Harvest your radishes when the roots -- the actual radish -- measures 1 inch or less in diameter.
Squeeze large or questionable radishes to determine if they are too old to eat. If the radish yields to pressure and does not feel firm and crisp, the vegetable is probably fibrous and will have a spongy texture.