How do you correct the following sentence Leah read avidly about gardening although she had never planted one herself?

One what? 'one' needs to link back to a thing mentioned earlier in the sentence. So you could say Leah read avidly about GARDENS although she had never planted one herself. then 'one' means 'a garden'. Or you could say 'Leah read avidly about garnening although she had never planted anything herself' (I'm avoiding saying 'planted a plant' because it sounds silly).