The choice of plants for nursery production is governed by several factors: market demand, production requirements, and production capabilities. Market demand is the driving force that dictates what plant species will sell, by whom they are sought, what sizes are desired by the purchasers, and what quantities of each species and size will be required. Plants headed for garden centers and other retail outlets for homeowner purchase are often smaller than plants used by landscape contractors. Nurseries frequently specialize in the production of plants for one type of market rather than trying to serve them all.

Production requirements are simplified when the grower limits the choice of plant species to those having similar propagation methods, nutrient and water needs, pest control requirements, light needs and tolerances, spacing, and harvest methods. Such simplicity and spe­cialization saves time and avoids the costs required to produce a more diverse, less homogeneous array of species.

Production capabilities can be developed to parallel the require­ments for crop production. Only facilities, tools, and equipment required for the crops being produced need to be purchased. Capital is not tied

up in expensive machinery or buildings that are required only infre­quently, or for the production of a species marketed in small quantities or that return small profits.

There are limits to the simplification of crop choices, however. One reason is the public interest in new varieties of plants that is increas­ing the demand for a wider array of plant species in the marketplace. Another limit is the danger of great financial loss to the nursery grower who grows only a few species. A severe insect or disease infection or environmental calamity can wipe out years of effort and investment almost overnight. A change in market demand can be almost as disas­trous. In nursery production, as in all areas of agricultural production, monocultures should be avoided.