Horticulture, literally garden culture, is a part of crop agriculture that also includes agronomy and forestry. By tradition, horticulture deals with garden crops such as fruits, nuts, vegetables, culinary herbs and spices, beverage crops, and medicinals, as well as ornamental plants.
Agronomy is involved with grains, pasture grasses and forages, oilseeds, fiber crops, and industrial crops such as sugarcane, while forestry is involved with trees grown for timber and fiber as well as the incidental wildlife. The edible horticultural crops are used entirely as human food and are often utilized in the living state and thus highly perishable. In contrast, edible agronomic crops are often utilized in the nonliving state, are highly processed, are often used for animal feed, and usually contain a high percentage of dry matter.
The precise distinction between horticultural and agronomic crops is traditional. In general, horticultural crops are intensively cultivated and warrant a large input of capital, labor, and technology per unit area of land, but in modern agriculture, horticultural crops may be extensively grown while many agronomic crops are now intensively cultivated. Many crops are claimed by more than one discipline.
Horticulture is practiced in large agricultural operations, in small farm enterprises, and in home gardens.
Horticulture is associated with a number of intensive practices that collectively make up the horticultural arts. These include various propagation techniques incorporating special plant structures such as bulbs, corms, or runners; the use of layers or cuttings; budding and grafting; and micropropagation involving tissue culture.
Cultural practices include soil preparation, direct planting or transplanting; fertilization; weed, disease, and pest control; training and pruning; the use of controlled environments such as greenhouses or plastic tunnels; applications of chemical growth regulators; various harvest and handling methods; and various postharvest treatments to extend shelf life. Other practices associated with horticulture are breeding and genetic techniques for crop improvement, marketing methods, and food processing. Ornamental horticulture, not considered here, includes added practices associated with landscape architecture and the floral arts.
While horticulture is an ancient art with many of its practices empirically derived, present-day horticultural arts are intimately associated with science, so that modern horticultural science is one of the most advanced parts of agriculture. Recently some horticultural growers have attempted to reduce or even eliminate reliance on inorganic fertilizers and pesticides through the incorporation of ecologically based practices (integrated crop management).
Horticultural Food Crops
Horticultural food crops include an enormous array of species that are grouped in various ways.
Fruits of woody perennial plants have long been prized for sources of refreshment, for their delightful flavors and aromas, and as nourishing foods. Fruit crops can be defined as temperate, subtropical, and tropical depending on their temperature requirements. Temperate fruits are deciduous (drop their leaves in the cold period) and undergo dormancy requiring a certain amount of low temperatures (chilling period) before growth is resumed in the spring. Subtropical fruits require a very short chilling period. Tropical fruits are usually evergreen and are extremely cold-sensitive. Within these groupings fruit crops are usually grouped by taxonomic affinity. The temperate fruits include the pome fruits (apple, pear, quince, medlar), stone fruits (apricot, cherry, peach and its smooth-skin variant the nectarine, and plum), vine fruits (grape and kiwifruit), and small or bush fruits (strawberry; blueberry, cranberry, and lingonberry; brambles such as blackberry, raspberry, and various hybrids; currants and gooseberries). The subtropical fruits include citrus (citron, grapefruit, the tropical pomelo, sweet orange, lemon, lime, mandarins, and various hybrids such as the tangor or tangelo); and fruits associated with Mediterranean climates (avocado, cactus pear, carob, fig, loquat, persimmon, pomegranate). There are hundreds of tropical fruits, of which the most important are banana and plantain, mango, papaya, and pineapple, but there are hundreds of others with regional interest, including acerola, akee, carambola, cherimoya, durian, guava, litchi, mangosteen, passion fruit, rambutan, sapodilla, and soursop.
The important tree nuts that enter into international trade include almonds, Brazil nuts, cashews, chestnuts, hazelnuts, macadamias, pistachios, pecans and hickories, and walnuts.
Beverage crops include the subtropical crops—coffee, tea, and maté—and the tropical cacao used for cocoa and the confection chocolate.
Vegetables are typically herbaceous (softstemmed) plants in which various parts are used as food, including roots, tubers, leaves, fruit, or seed. There are various groupings based on the part consumed and taxonomic affinity. Vegetables include the root crops (beet, carrot, cassava, celeriac, dasheen, horseradish, parsnip, potato, salsify, turnip, radish, rutabaga, and sweet potato, as well as some little-known Andean tubers such as oca, mashua or anu, and ulluco, and root crops such as arracacha, maca, and yacon); bulb or corm crops including the pungent alliums (chive, garlic, leek, onion, shallots, and chive); salad or leafy crops (arugula or rocket, celery, chicory, cress, endive, lettuce, parsley); cole crops or crucifers (cabbage, cauliflower, broccoli, brussels sprouts, kohlrabi, Chinese cabbage, and various Asian types such as bok choy); potherbs or greens (chard, collards, dandelion, celeriac, kale, mustard, orach, spinach, New Zealand spinach); solanaceous fruits (eggplant, sweet and hot peppers, tomato and husk tomato), cucurbits, also known as melon or vine crops (chayote, cucumber, muskmelon, pumpkin, squash, watermelon); legumes or pulse crops in which the seed is consumed (adzuki bean, broad bean, chickpea, common bean, cowpea, lima bean, mung bean, rice beans, tepary bean, urdbean, garden pea, and pigeon pea). Some vegetables are perennial (artichoke, asparagus, Jerusalem artichoke, rhubarb, sea kale). Some agronomic crops are consumed as a vegetable in various stages, and these types are included as horticultural crops. Examples include sweet corn (the immature ears of a sweet type of maize), immature vegetable soybean or edamame, and the young leaves of amaranth.
Culinary herbs and spices.
Aromatic plants used for culinary purposes are called herbs when they are temperate species and spices when they are tropical. Examples include allspice, anise, basil, capsicums, caraway, cardamom, cinnamon, chervil, clove, coriander, cumin, dill, fennel, funugreek, garlic, ginger, laurel, marjoram, mint, mustard, nutmeg and mace, onion, organum, parsley, pepper, poppy seed, rosemary, saffron, sage, savory, sesame, star anise, tarragon, thyme, and turmeric.
The field of horticulture has a great many organizations and societies devoted to all phases of horticulture, including amateurs and fanciers, growers and handlers, researchers, and academics. There are plant societies devoted to individual or groups of crops, trade organizations devoted to the production and marketing of individual horticultural crops, and scientific societies devoted to scientific research. In the United States, the principal society devoted to the science of horticulture is the American Society for Horticultural Science (founded 1903) with offices in Alexandria, Virginia. The society publishes three scholarly journals as well as books, and conducts annual meetings. Examples of other scientific societies in the United States include the American Pomological Society, devoted to fruits and nuts, and the American Potato Society. Growers of horticultural crops are also organized in state societies. Many countries have a national scientific society devoted to horticulture. The International Society for Horticultural Science located in Leuven, Belgium, sponsors international horticultural congresses every four years.
Horticulture is a recognized part of the curricula in agriculture worldwide. In the United States many land grant universities have horticulture departments devoted to undergraduate education leading to the B.S. degree. Most of these departments provide advanced training leading to the M.S. and Ph.D. degree. However, since the 1990s there has been a trend for horticulture and agronomy departments to combine into either a Crop Science or Plant Science department. A number of schools give two-year programs leading to associate degrees.