groundskeeping vs horticulture

groundskeeping

noun
  • The activity of tending an area of land for aesthetic or functional purposes; typically as an employee of a person or institution 

horticulture

noun
  • The art or science of cultivating gardens; gardening. 

  • Small-scale agriculture. 

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