Save the radish seed packet when planting. Refer to the harvest time listed on the packet to know when to pick your radishes. You want to start checking your radishes once you enter that harvest window.
Brush the top layer of soil away from around the base of the radish plant. Radishes are ready for picking when you notice swollen bulbs around 1 inch in diameter. The bulbs may even poke through the top layer of soil on their own.
Grasp a radish plant at the base and pull it straight out once you have followed Steps 1 and 2. Prepare the radish and take a bite. If good flavor exists, pull a few more out and see that they are around the same size as the first.
Harvest the rest of the radishes and either prepare them for storage or eat them. If radishes stay in the ground too long they will become hot, tough and bitter.