Radishes have a tangy kick to them and add a satisfying crunch to salads and other dishes. Growing radishes in containers allows you to plant them in early spring before a garden bed would be ready to plant. Early planting gives cool-season radishes the time they need to reach maturity. Containers also drain better than garden beds, and proper drainage prevents the radishes from rotting in the cool soil.
Fill a 9- to 12-inch deep container with a sterile peat- or vermiculite-based potting soil. Use a container that is at least 12 inches in diameter and has drainage holes in the bottom.
Sow radish seeds 1 inch deep once daytime temperatures are steadily above 55 degrees Fahrenheit. Space the seeds 2 inches apart in all directions.
Water the container after planting until the excess water begins draining from the bottom of the container. Irrigate thereafter when the top ½ inch of soil begins to feel dry. In containers, this may be as often as once a day.
Fertilize radishes every two weeks with a half-strength soluble fertilizer that is rich in nitrogen. Follow label instructions for exact application methods, though generally ½ tbsp. of soluble fertilizer is mixed with 1 gallon of water, then the radishes are watered with the solution.
Harvest radishes when they reach maturity, which is indicated on the seed packet. Most varieties reach harvestable size withing 30 to 45 days. Pull the roots up by the foliage then trim off the leaves before use or storage.