greenhouse vs propagate

greenhouse

verb
  • To nurture in order to promote growth. 

  • To place (plants) in a greenhouse. 

noun
  • A building used to grow plants, particularly one with large glass windows or plastic sheeting to trap heat from sunlight even in intemperate seasons or climates. 

  • A hot state in global climate. 

  • A structure that shields the operating table to protect against bacteria. 

propagate

verb
  • To produce young; to be produced or multiplied by generation, or by new shoots or plants. 

  • To cause to take effect on all relevant devices in a network. 

  • To spread from person to person; to extend the knowledge of; to originate and spread; to carry from place to place; to disseminate. 

  • To cause to spread to extend; to impel or continue forward in space. 

  • To cause to continue or multiply by generation, or successive production. 

  • To generate; to produce. 

  • To take effect on all relevant devices in a network. 

How often have the words greenhouse and propagate occurred in a corpus of books? (source: Google Ngram Viewer )