I am currently reading Fern Fever by Sarah Whittingham. It is a history of the Victorian craze for ferns (collections displayed in fern houses, rockeries and the the Watsonian Patent Fern Bricks). This is the sort of book I love - it teaches you something entirely new, and you are a (slightly) different person after reading it.
If you want to see ferns I can recommend Abney Cemetery in north London. Lushly luxuriant, delicately scented and soothingly green. The stone angels seem to float above the foliage.
Many famous people are buried in Abney Cemetery, including the founders of the Salvation Army. But it is the more ordinary graves, smothered in greenery, that are most poignant. How confident these bourgeois Victorians were that a grave in Abney would ensure a high status for eternity.