To prolong their lives as cut flowers, lilies are harvested before they open. The most mature buds will open in a few days, while the smaller buds will mature and open over the nest week or two. If you need your lilies for a special event, however, you may need them to open before they are ready. If the buds on your lily stem are mature -- you'll have the best success with buds that are already beginning to crack open -- it is possible to force them open over the course of one or two days.
Fill a vase half-full with warm water.
Add 2 tbsp of table sugar per quart of water in the vase.
Place the lilies in the vase.
Cover the top of the lilies loosely with a clear plastic bag. Cinch the mouth of the bag tight around the vase with string or a twist tie. The bag and the warm water will humidify the air around the lilies and encourage them to open.
Place the vase in a warm spot, away from a window where it will only receive indirect sunlight.
Remove the bag and check on the lilies the next day. The most mature buds may have opened. If the buds remain closed, you may replace the bag.
Remove the flowers from the water when the buds have opened or after 24 hours have passed. The stalks must not remain in the sugar water for longer than 24 hours.
Fill the vase with room-temperature water and replace the lilies if they have opened. If they have not opened, fill the vase with warm water and replace the bag. Remove the bag after three hours and change the water. Then, three hours later, change the water again and replace the bag. Keep changing the water every three hours and keeping the bag on for three hours then off for three hours until the mature lily buds open.
If the lily bud is mature and the tips and sides of its petals are beginning to split open, you may force them open with your hands. But keep in mind that there is a high possibility that you will tear the petals and ruin the flower. Prune the anther from the centre of the lily once it opens. It will keep pollen from staining the petals and increase the longevity of the lily. Never buy cut lilies that have had all of their leaves removed. A cut lily still needs its leaves to provide the energy required to mature and open closed buds. It can take as long as 72 hours for a closed, mature bud to open.