See, the sugar is a feast for bacteria in the water, and since rose stems don't have much of a microbiome to protect them, those bacteria can get inside and plug them up, keeping the flower from getting enough water.
细菌喜欢的大餐就是水中的糖类,而且由于玫瑰根茎几乎没有什么微生物群来保护它们,这些细菌一进入根茎堵个水泄不通,使得玫瑰花无法获得充足水分。