How to Propagate radish 'Amethyst'?
Propagate by seed. See sowing vegetable seeds

radish 'Amethyst' · Raphanus sativus 'Amethyst'
Grow in any moisture-retentive soil as long as it isn't too acidic, in full sun. Extremely quick to harvest, so can be fitted into very short time-slots/limited spaces. For more advice see vegetable cultivation
Propagate by seed. See sowing vegetable seeds