Many times roses or lilies will be purchased in bud form or more closed. This helps prevent damage in shipping and allows you to enjoy the opening process of these specific flowers. Roses need the flower nutrient and light to open. When you purchase roses and would like them to be more open for a special occasion it is best to get them several days ahead of the event, allowing them plenty of time to open in a 70-degree room with plenty of indirect light.
Lilies on the other hand can benefit from a trick! Cut the stems of the lilies (about 1 inch off the bottom of the stem) and lay them on the counter out of water for approximately one or two hours. The lily will be limp and dehydrated after this time. Re-cut the stem and place into cool flower nutrient water. This seems to increase the hormones in the stem and the lily will open faster.