Plant short-season or spring varieties in spring or fall, depending on local temperatures. Ideal growing temperature is 60° F to 65° F. Cooler or warmer weather results in harsher-tasting radishes. Plants will mature in 18 to 45 days, depending on variety.
Plant winter types in the summer or fall, depending on the variety; they mature in 45 to 70 days.
Spring radishes can be planted right next to rows of larger, slower crops - no need to create a separate radish bed.
Sow radishes directly in the garden. Plant spring varieties 1 inch apart, 1/2 inch deep.
To get larger spring radishes, plant seeds 1 1/2 inches deep, 1 1/2 inches apart, in rows 24 inches apart.
Plant winter radish varieties 1 to 3 inches apart.
When young radishes are 1 inch tall, thin to 2 to 3 inches apart.
Provide even watering. Heat and too little or uneven watering can result in tough, pithy, very hot radishes.
See our article Summer's Bad Guys by Charlie Nardozzi for controls of common radish pests such as root maggots.
Pick spring varieties as soon as they reach the size you prefer.
Before they become tough and pithy, pull all the radishes, trim off the tops, and store in plastic bags in the refrigerator.
Winter varieties will keep adequately in the ground for a few weeks after maturity, in cool weather. Store these radishes through the winter as you would carrots or beets, in sawdust or peat moss.