Why should you remove leaves in a vase?
Leaves contaminate the vase water, just like stems do. The stem has to be in the water. The leaf however serves no purpose in the water. In fact, it has a negative effect! Therefore, it is recommended to remove the lower leaves which would otherwise be in the vase water. The additional positive effect of this is that it decreases the amount of evaporation because the total leaf surface is decreased.
All of the contamination, remnants of fertilizer, plant protection products and micro-organisms travel along with the leaves and contaminate the vase water, the so-called bio-load of the vase water. In this case, hygiene and prevention of infection of the vase water provide the best contribution to a long vase life and vase water that is not smelly. That is why you should remove all leaves and the leaf remnants that are in the vase water.