Complex sentence: It is rare for one kept as a a houseplant to flower; nevertheless, a fifty year old blue agave in Boston has grown a 10 m (30 ft) stalk requiring a hole in the greenhouse roof and flowered sometime during the summer of 2006.
Split into simpler sentences: It is rare for one kept as a a houseplant to flower. A fifty year old blue agave in Boston has grown a 10 m (30 ft) stalk requiring a hole in the greenhouse roof and flowered sometime during the summer of 2006.