The amount of time it takes a red radish to mature depends on the type of radish seeds you plant. Red radish varieties include Champion, Cherry Belle, Cherry Queen Hybrid and Early Scarlet Globe.
Red radishes grow best when planted during the cooler temperatures of the spring season. Radishes need regular watering and may mature quicker if you mix fertilizer into the ground soil of the planting site.
You can harvest Champion radishes 28 days after sowing; Cherry Belle radishes take 22 days to mature. Early Scarlet Globe radishes mature about 23 days after planting. Cherry Queen Hybrid radishes are ready 24 days after sowing, according to the University of Illinois Extension website.
Thin out radish seedlings so the plants have room to mature. Space spring variety red radishes between half an inch and one inch apart, according to the University of Illinois Extension.