You do not need to be a scientist or horticulturist to regrow radishes. You can make more radishes from radishes by replanting the root. Other parts of the radish will not regrow if you plant them again. If you do live in an area that does not freeze, you can plant radish seeds or roots year-round.
Cut the radish 1 inch from the root end using a kitchen knife. Collect the root ends for planting. The radishes should be cut before harvest to provide the largest roots for regrowth.
Cover the entire cut surface of the radish root in germination gel. Spread the gel over the surface evenly using your fingers.
Dig a hole 2 inches in the soil using a garden hoe. Place the root end into the hole and cover the hole with soil.
Dig a row of holes 2 inches apart from each other. If you dig another row, space the row 10 inches from the previous row.
Store the other radishes for future use.
Germination gel is sold in your local hardware or home and garden store.