Radishes should be planted in an area with full sun or partial shade, and loose, well-drained soil. Remove any rocks from the soil, as the roots will bifurcate around any rocks in their way. Add organic matter to the soil before planting, such as compost, manure, or leaf mold.
Radishes are a cool weather crop best planted in spring and autumn. Growing radishes during the hot summer months may cause them to bolt. You can plant your first crop a full 2 weeks before the last frost in spring, as radishes endure frost well.
Because radishes grow so quickly, you can "inter-crop" them between slow-growing vegetables to make row markers. You can also "succession plant" them by sowing a new row each week, to spread your harvest over a longer period.
You will want them to be about 1/4 inch deep and 1 inch apart. As they germinate, thin the successful seedlings to about 2 inches apart, allowing more space for bigger varieties. Rows should be planted about 1 foot apart.
Keep the radish beds moist, but not soaked. Watering radishes frequently and evenly will result in quick growth; if radishes grow too slowly, they will develop a hot, woody taste. Add compost to the radish bed as desired to help retain moisture.
Radishes are typically ready to harvest when their roots are about 1 inch in diameter. Check your seed packet for your variety's expected size at harvest and time to maturity. To harvest, lift the entire plant out of the ground with your hand.
Read more here: https://sowtrueseed.com/blogs/gardening/how-to-grow-spring-winter-radishes