These hobbyists, whose pastime is gardening, regularly buy books on topics like how to garden year round regardless of the outdoor weather; grow hydroponic produce to increase yields and conserve space; grow cuttings so flowers bloom sooner on compact plants; garden in a non-toxic environment organically; control the environment in the garden to exclude toxic pollutants; grow exotic tropical plants in any climate; start seeds and cuttings indoors to move outdoors; and many other issues involved in indoor gardening. In addition, they read about the more general gardening subjects such as pest and disease control, weed control, plant propagation, soil amendments, etc. Source: specialty book shops, gardening clubs.