Ideally, a person would like to leave the lilies in the ground until the leaves turn yellow/brown and fall sometime in October. Because the second half of the season is when the bulb is rebuilding itself for next years performance. When that is not possible, then the next best option is to dig them as a clump and transfer the whole plant into a large pot temporarily. Add enough soil to completely cover, water in well and store in a cool shade location if possible until ready to replant in your new garden later this fall (after the leaves have turned yellow and fallen. If you have more questions as you move ahead with your project, just ask.
