Rose Garden II
Rose Garden II
Brown, Betsy
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The word "horticulture" is formed from two Latin words -- "hortus," meaning "garden"; and "cultura," meaning "cultivation." Horticulture is a branch of agriculture, which is the science of farming, or the cultivation and management of plants and animals to supply man's needs. Anthropologists define horticulture as plant cultivation without a plow; and agriculture as plant cultivation with a plow. Horticulture is concerned primarily with growing fruits, vegetables, herbs, and ornamental plants in gardens while agronomy, another branch of agriculture, is concerned with managing and growing large field crops, such as wheat and rice. The science of horticulture is closely intertwined with the science of botany, the study of plant biology. Among the sub-categories of horticulture are floriculture (growing flowers), olericulture (growing vegetables), pomology (growing fruit), viticulture (growing grapes for wine) and landscape gardening.

The division of plant cultivation into the disciplines of horticulture, agronomy and forestry came out of the manorial system of Europe's Middle Ages. The concept "horticulture" derived from the cultivation of fruits, vegetables and herbs in enclosed gardens near a manor house; "agronomy" from the cultivation of larger crops in open fields further away from the manor house; and "forestry" from preservation of the wild areas furthest away from the manor house for game and forest products.

Today horticulturists work within all three disciplines but focus largely on gardening. Gardening is the cultivation of plants within a relatively small designated area, such as in borders or enclosed spaces around a building, in a greenhouse, or in a container. Landscape gardening also includes the design and maintenance of areas such as sports fields, golf courses, public parks and cemeteries.

Horticulturists need to know as much about plants as doctors know about people and as veterinarians know about animals. They must know about plant nutrition and how to treat plant injuries and diseases. To grow plants successfully, one must consider many factors, among them climate, terrain, latitude, and altitude; plant growth and dormancy cycles; differences in plant species; plant parts; availability of light, water and plant nutrients; plant pests and diseases; and how plants are propagated. Also to be considered are the "personalities" and physical strengths of individual plants of the same kind -- like people, no two plants are alike. Two red roses of exactly the same kind planted next to each other often will perform differently.

Plant RX: How to Diagnose Plant Problems

Growth Determinants

Climate, terrain and latitude are the major determinants of how and whether a plant will grow and survive. Different plants require different conditions of temperature, length of growing season, length of daylight, exposure to sunlight, rain and soil nutrients. Even the mini-climates and position of plants within an individual yard will affect plant vigor and viability. Latitude is very important to a plant's viability because of differences in temperature and length of day at various points on the earth. World maps of plant hardiness zones have been developed to aid horticulturists and gardeners determine the climatic temperature range within which they garden and which plants are suitable for that range. Plant catalogs and nurseries often refer to these zone numbers when describing plants. Not only the length of day, but also the amount of sun to which a plant is exposed within a day, affects individual plants differently. Most roses, for instance, need six hours of sunlight a day to perform at their peak, while some plants, such as hostas, are shade-loving.

GARDENING TOOLS

The consistency and chemical composition of soil also greatly influence plant viability. Some plants prefer a more sandy soil, while others prefer a more clayish soil, and some plants can grow in water without any soil at all. Some plants do well in water-logged soil, while many need good drainage. The pH of soil and the nutrition it provides is vital to a plant's viability. Some plants prefer a more alkaline soil, while others prefer a more acid soil. Most temperate-zone ornamental plants, for instance, grow best in neutral or slightly acid soil, although some, such as lilacs, prefer a more alkaline soil. The most fertile soil for most plants looks like crumbly chocolate cake and is called "black gold" by gardeners. Soils can be amended in a garden or around a particular plant by adding appropriate ferlilizers. Composting the debris of a garden's plants is one way to produce fertilizer. Good horticulturists also must consider how the kind and amount of fertilizer they use will affect the environment around them. Large amounts of fertilizer that soak into ground water and then wash into streams and rivers can cause serious water pollution.

Life-threatening injuries to plants can be caused by weather, people, animal and insect pests, air pollution and diseases. Like people, plants can be infected by a variety of bacterial, fungal and viral diseases. They also can be threatened by competition for nutrients and space from other plants, such as weeds. These threats to plant health can be controlled by applying the appropriate insecticides, fungicides or herbicides; or, in the case of injury, by appropriate pruning, support or protection. For plant viruses, however, there are no "medical cures," just as there are no cures for the common colds and flus that infect people. Knowing how to prevent plant diseases and injuries is as important as knowing how to treat them.

Treatment of plants also varies with the type of plant. Plants fall into three major categories -- rooted, woody plants (trees and shrubs), which remain standing year-round; herbaceous plants that die back to the ground each year, such as annuals, biennials and many flowering perrennials; and bulbs. Methods of propagating plants vary accordingly. Plants can be propagated in several ways: they can be grown from seed, or they can be cloned by dividing the roots or bulbs of an established plant, or by taking a cutting of an established plant. Choosing a propagation method can be crucial in food production and garden design. Plants grown from seed will not have the exact attributes of their parent plants -- just as human children do not look exactly like either of their parents -- because each new, "original" plant will have its own genetic code. Plants that are cloned, however, will be exactly like the plant from which they were taken.

How to Propagate Plants

Design

Horticultural design is an important subdivision of the discipline. Some horticulturists go into landscape architecture, garden design or floral design. These specialists need to know not only the universal artistic concepts of color, shape, space and texture, but how plants grow and in which conditions which plants perform best, so that they can achieve different effects. Designing with plants is a three-dimensional art form because the designer must know when each plant in the design will bloom and go dormant or expire, what colors each plant will produce, and how large each plant will grow, so that no "holes" of color, space or shape will be left when individual plants lose their leaves or blossoms. Some garden designers and gardeners also employ artistic plant-shaping techniques such as topiary (training, cutting, or trimming), espalier (training to grow on a support), and pleaching (intertwining branches that form a hedge). In some cases, such as in the cultivation of hydrangeas, they may apply different chemicals to achieve different flower colors. Many horticulturists and gardeners also experiment with grafting and hybridizing plants in order to create new plant colors, shapes or sizes, or plants that are more resistant to particular plant problems. An especially important field of horticulture is the hybridization of edible plants in order to create new crop strains that are more hardy or productive.

Botany

Emil Nolde - Botanical Studies III
Botanical Studies III
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Botany is the study of plants. The kingdom Plantae is divided into divisions (the term "division" was traditionally used instead of "phylum" as in the animals, but either term is now accepted).

  • Hepatophyta, liverworts
  • Anthocerophyta, hornworts
  • Bryophyta, mosses
  • Lycophyta, club mosses
  • Psilotophyta, whisk ferns
  • Sphenophyta, horsetails
  • Pterophyta, ferns
  • Cycadophyta, cycads
  • Ginkgophyta, ginkgo tree
  • Gnetophyta
  • Coniferophyta, conifers
  • Anthophyta, flowering plants
    • Liliopsida, monocots
    • Magnoliopsida, dicots

Of these, the best known to most people are Bryophyta (mosses), Pterophyta (ferns), Coniferophyta (conifers), which are cone-bearing plants, and Anthophyta (angiosperms), which are flowering plants. Angiosperms are divided into two groups, dicots and monocots. Dicots have two cotyledons (embroyonic leaves), while monocots have only one cotyledon.

The names "Pinophyta" and "Magnoliophyta" are often used for "Coniferophyta" and "Anthophyta". Likewise, the monocots and dicots are called "Liliopsida" and "Magnoliopsida" respectively.

Gardening Posters

by FM