Approximately one week. Keep soil moderately moist during germination. Ed's Special Advice Treat soil with safe insecticide to protect from root insects, or sow seed where radishes or cabbage had not been grown the previous year. Protect seedbed from new infestation with cheese cloth or agricultural netting strung above plants. Sow seeds every 2 or 3 weeks for continual harvest.
Radishes grow best during the cooler parts of the growing season.
Plant in a mostly sunny spot in moderately rich soil kept fairly well watered.