Whether you grow your own or purchase them, lilies make great cut flowers to use in a vase or floral arrangements.
When cutting fresh lilies from your garden to enjoy indoors, leave 1/2 to 2/3 of the stem of the plant so it will not harm the plant for future bloom.
For maximum enjoyment, cut them early in the morning, when they
are just about to open. Use a sharp knife or shears for a clean cut. Remove lower leaves that may be underwater and place your cut flowers in tepid water with floral preservative.
When the buds start to open, remove the anthers (male part of the plant with the yellow pollen). This will lenghten the life span of the flowers and avoid petal stain.
Take care not to get pollen on your clothes as it will also stain. If you do, brush it off with a dry paper towel, that should remove most of it.
Store your lilies in a cool room away from direct sun, cold drafts and heating vents.
If the buds are tight and you need opened flowers, here’s something you can do to coax them to open.
Recut the stems and place them in lukewarm water with cut flower food. Warmer water will open them faster. Another trick is to place a plastic bag over the whole bucket of stems to increase the humidity and temperature. The cut lilies should start to open in a day or so. Keep the bucket away from direct sun until you remove the plastic cover. When the buds start to open, remove the pollen from the stamens. This will prolong freshness and avoid any pollen stains.
If the buds don’t open, they may have been damaged from poor storage such as ethylene gas exposure. If the lilies start to open too fast, place them in a cooler environment away from light.
Optimally, cut lily* stems should last 7-14 days. Individual flowers last 4-7 days.
*depends on variety
more info: http://hortchat.com/info/stargazer-lilies