I believe that‘s the theme song 《初恋女》of the movie 《初恋》(first love)which was released in 1937. The lyric was written by famous poet Dai Wangshu (戴望舒). The original sentence is 终日我灌溉着蔷薇,却让幽兰枯萎。 One tricky thing is 月季,蔷薇 and 玫瑰all translated into ‘rose‘, while the first two are very common in classical Chinese, 玫瑰, instead, is a symbol from the western world and rarely seen before late Qing Dynasty.
Back to the lyric it self, Jeff has given nice explaination. These two flowers usually being used to describe women with different characteristics. It is said that the orchid refers to poet's first girlfriend, 施绛年 (the younger sister of 施蛰存,the famous scholar), while the prickly rose refers to his wife, 穆丽娟 (the younger sister of writer 穆时英). There are also rumors said that 穆丽娟 was angry about this poem. Therefore it can be also explained as the choice between morality and love.