When your flower opens, we recommend that you reach into the flower and remove the anthers: these are the 6 yellow pieces that surround the sticky, bulb-like pistil in the center of the flower. We do this routinely at Behnke’s, so any open flowers on your plant have already been “cleaned.”
If not removed, after a day or two, the pollen will ripen and become dusty, and it will fall on the flower and stain it yellow. All it takes is a gentle tug. If the pollen is already dry, it will come off on your hands. If it gets on your clothing, you will have to wash the garment; so best remove the anthers when they are young.
A note to cat owners: lilies are poisonous to cats. Plant some “cat grass” for them to chew on.