A couple lily plants in a garden will turn into many in just a couple years. That is because lilies have root system called bulbs, which self propagate. Fortunately, the bulbs can easily be transferred from one area to another. Transferring becomes necessary when your garden becomes overcrowded and too many plants are using the same water and nutrients and blooms are therefore scarce. You can either transplant the whole plant or just the bulbs.
Prepare the new planting bed. Till about 12 inches deep and add a couple inches of organic matter such as compost or peat moss. This will make the soil more conducive to growing lilies.
Wait until the leaves turn yellow or brown if you are planning on only transferring the bulbs to a new location for the next growing season. This usually occurs after the first frost. Cut the foliage off so that only a couple inches remain. Allowing the lily leaves to stay intact for so long lets the plants absorb lots of sunlight, which turns into sugar (food) through the process of photosynthesis. This will help the plants grow fuller with more blooms the next season.
Dig straight down--about 8 inches--around the perimeter of your plants. Then, start to pull down on your shovel or garden fork in several places to lift the bulbs out of the soil. Shake off the excess soil. Leave the foliage on if your plants are still green and you are transplanting the whole plants.
Plant your bulbs or whole plants. Bulbs should be planted 4 to 6 inches below ground with the tips facing up. If you are transferring whole plants, then plant them to the same depth they were previously planted.
Backfill the soil, push it down to remove any air pockets and water well. Push down on the soil with your hands again to be sure you've eliminated all the air pockets, which can inadvertently cause root rot.