Interplant with Lettuce
Because radishes grow so quickly, you can add a dotting of seeds to the garden or containers each week for a continuous supply. Radishes like to be interplanted with lettuces; this helps keep the soil moist and makes them sweeter. So after sowing our first crop with carrots, we planted a second with a spring crop of lettuces. You can also plant radishes between larger, slow-maturing vegetables, such as spring broccoli, which needs 2 months to mature. By the time the broccoli grows tall enough to cast shade, the radishes are ready.