Cut Lily of the Nile flowers in the early morning hours or later in the evening after the sun goes down. During the day, the heat and intensity of the sun stresses the plant. Cutting them in the middle of the day results in a weak, droopy flower.
Wait for the flower buds to start to open before you cut them. The buds open fully after you cut the flowers.
Use a pair of sharp garden shears to cut the Lily of the Nile stems. Cut the stem as far down as possible, slicing each stem at a 45-degree angle. You will cut the stem again later to a more manageable length.
Fill a vase or large container with warm water and put the cut Lily of the Nile flowers in it. Remove any foliage that is under the water when you put the flowers in the vase. Set the vase in a dark spot overnight.
Remove the flowers from the vase and cut the stems again to the desired length. Place the flowers in a vase filled with clean water.