Split daffodils when the foliage yellows. Do not cut down the foliage, though, because it will help you locate the bulbs beneath the soil.
Push the shovel into the soil about 6 inches away from the center of a daffodil plant. Keep digging all the way around the edges to dig a circle. Dig at least 6 inches down into the soil and then gently angle the shovel beneath the bulb to lift it from the soil.
Grasp the bulb by the foliage and shake off the loose soil.
Examine the bulb, looking for any unhealthy portions. Break any soft or decaying portions of the bulb off with your hands and discard.
Break apart the bulbs, separating the newer bulb growth from the original bulbs. Cut off the stems just above the bulbs with the pruning shears.
Dig new holes for the split daffodil bulbs, spacing the holes about 6 inches apart and digging them between 5 and 6 inches deep.
Plant the newly split bulbs immediately, placing each bulb in a prepared hole with the roots facing down and the stem ends facing up. Cover the bulbs with soil.
Water the newly split and planted bulbs thoroughly to saturate the soil evenly.