Overcrowding is the main reason for dividing bulbs.
image by Andrea Kratzenberg/sxc.hu
True bulb plants consist of flowers such as lilies, daffodils, tulips and crocuses, just to name a few. When dividing bulbs, it is best to wait until fall when the foliage has died off, although it can be done anytime. It is time to divide your bulbs when the area becomes overcrowded. One sign that the bulbs are overcrowded is that the plants don't bloom like they should, as too many bulbs are using the same water and nutrients.
Remove the bulbs from the ground, carefully. With the shovel, dig straight down about 6 to 8 inches around one plant. Then, pull the handle down toward you to lift the bulb out of the ground. Repeat on the opposite side if necessary. Dig the rest of the bulbs out in the same manner.
Remove as much dirt as possible with your hands. Shake if necessary.
Look at the bottom of the bulbs. This is where the new bulbs will be growing. Just pull them apart with your hands. You should not need any tools do this; however, if it is just slightly attached, use a knife to help the process. For lily bulbs, you will need to remove the outer skin to reveal the new growing bulbs.
Plant or store the bulbs immediately. It is best to replant them; however, if it is too cold store them in a dry, cool location like a crawl space or basement. For lilies where some of the skin is removed, dip the ends of the bulbs in rooting hormones before replanting. Rooting hormones are available at most nurseries.