How to care for your calla lilies and roses wedding mix Upon receiving your flowers, inspect all bunches, take them out of the box and remove all packaging. The flowers may appear limp or tired after their journey and this is completely normal. Large calla lilies: Large callas require at least 6 hours in water to re-hydrate after their trip and blooms will open in approximately 1-3 days. Hold the ends of the stems underwater and trim them diagonally at least ¼ inch from the ends using a sharp knife. Roses: Cut stems diagonally approx 1 inch from the end under running water with a sharp knife. Remove all leaves that will fall below the water line.   Place all flowers immediately in clean vases or containers with lots of fresh water. Keep them in a cool, dim location, away from direct sunlight, draughts or excessive heat. To maximize vase life, re-cut the stems and change the water in the vases every day using the above steps.