Daffodils (Narcissus spp.) are among the most reliable perennial spring-flowering bulbs for the garden, and they naturally repel hungry rodent mouths and the nibbling teeth of deer. Digging up bulbs to relocate them or to divide the bulbs to expand the display can be undertaken many times of year as long as the bulbs are not damaged. For the coolest working weather and least worries or storage or bulb care, focus the digging in the autumn when you can immediately replant the bulbs and forget about them. Otherwise you need to let the foliage yellow and die to ensure the bulbs have energy to return next spring.
Mark the location of the daffodils you wish to dig up. Use a colored plastic flag on a wire that is often used by utility workers. Locate the flag directly over clumps of bulbs or to outline an area that needs complete digging to harvest hundreds of bulbs. Place these flags while the daffodil foliage is still present in late spring after the flowering display.
Write any notes on the flags with an ink pen, such as color of flower or anticipated number of bulbs that are in that "digging zone." Alternatively, use a piece of vinyl blind slat or a painting stir-stick as your plant area marker and write on those.
Wait until the usual daffodil bulb planting time in your area, which is from early to late autumn--in the United States that corresponds to September through November when the soil is not crusted by frost.
Find the daffodil clumps and dig the soil up with a potato fork. A potato fork is favored over a regular garden shovel since the fork's tines crumble the soil and allow you to dig a bit further away from bulbs, avoiding piercing or slicing them. Always dig 8 to 12 inches away from the plant marker in the first dig so you don't damage the core clump of hidden underground bulbs.
Immediately replant the bulbs to their new location once you've dug them up. Based on any notes on the markers, group similarly colored bulbs in a bucket and take them collectively to the new planting site. Remember to plant the bulbs two to three times deeper than they are tall; or, if you can recall, match the depth that they were growing in your new garden location.