Sentence:  Line the whole crust or fortifying boundary on its inside to the north, facing the south, with a conservatory for tropical plants, &c, that shall enclose twenty acres ; line it to the south, facing the north, with a conservatory of the same size for " <WSD>cold- natured</WSD> vegetation." 
Meaning of the word marked with <WSD> tags:  Thriving in colder environments.