Lilies are a large group of herbaceous flowering plants grown from underground bulbs that are fleshy and layered, resembling a small skinned onion. Unlike many bulb species that have a papery protective coating, go dormant and can be stored for extended periods, lily bulbs have no such protection and do not go dormant. Hence, they require special care in handling and storage so as to not be damaged or dry out before they can be planted.
Store your lily bulbs for short periods only when the soil is too cold to be worked easily or you are in the process of transplanting your lily bulbs to a new planting location. Otherwise, keep them in the ground soil and mulched over to prevent damage, bulb loss and disruption of the next season's bloom.
Prepare a storage container that allows some air flow but can be filled with and hold a fine textured storage medium. Breathable cloth bags, shallow wood, plastic or metal storage boxes without their lids will also work. Line the storage container with clean sand, wood shavings, sphagnum peat moss or vermiculite flakes. Sprinkle the storage medium lightly with a few drops of water so it is barely moist. As an alternative, prepare a nursery pot filled with potting soil for each lily bulb and plant them in the pot for transplant into the garden soil at a later time. Potting up the bulbs and transplanting the entire contents of the pot will preserve next season's bloom, as there is less movement stress on the bulb and roots. Sprinkle the potting soil with water as well, but do not soak the soil.
Nestle the bulbs into the storage medium or soil-filled nursery pot so that they are root plate down and slightly sloping side up. Cover them over with an inch-thick blanket of the medium. Keep the bulbs in a cool spot with temperatures consistently above freezing. Monitor the storage medium or soil weekly to ensure that it is just slightly moist and the bulbs are not drying out and shriveling. Sprinkle or mist more water as needed.
Transplant the lily bulbs into the garden soil after the ground has thawed in early spring or in the mid to late autumn, after temperatures have cooled but before the first hard frost. This timing allows the lily bulbs to enjoy the cool soil conditions they prefer and to begin rooting in advance of the extreme cold of winter or the heat of summer. Water the bulbs in well at planting.