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Companion planting

Companion planting

Overview
Companion planting is the planting of different crops in proximity (in gardening and agriculture), on the theory that they assist each other in nutrient uptake, pest control
Pest control
Pest control refers to the regulation or management of a species defined as a pest, usually because it is perceived to be detrimental to a person's health, the ecology or the economy.-History:...

, pollination
Pollination
Pollination is the process by which pollen is transferred in plants, thereby enabling fertilisation and sexual reproduction. Pollen grains transport the male gametes to where the female gamete are contained within the carpel; in gymnosperms the pollen is directly applied to the ovule itself...

, and other factors necessary to increasing crop productivity. Companion planting is a form of polyculture
Polyculture
Polyculture is agriculture using multiple crops in the same space, in imitation of the diversity of natural ecosystems, and avoiding large stands of single crops, or monoculture...

.

Companion planting is used by farmers and gardeners in both industrialized and developing countries for many reasons. Many of the modern principles of companion planting were present many centuries ago in cottage garden
Cottage garden
The cottage garden is a distinct style of garden that uses an informal design, traditional materials, dense plantings, and a mixture of ornamental and edible plants. English in origin, the cottage garden depends on grace and charm rather than grandeur and formal structure...

s in England and home gardens in Asia.

For farmers using an integrated pest management
Integrated Pest Management
Integrated pest management is an ecological approach to agricultural pest control that integrates pesticides/herbicides into a management system incorporating a range of practices for economic control of a pest...

 system, increased yield and/or reduction of pesticides is the goal.
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Encyclopedia
Companion planting is the planting of different crops in proximity (in gardening and agriculture), on the theory that they assist each other in nutrient uptake, pest control
Pest control
Pest control refers to the regulation or management of a species defined as a pest, usually because it is perceived to be detrimental to a person's health, the ecology or the economy.-History:...

, pollination
Pollination
Pollination is the process by which pollen is transferred in plants, thereby enabling fertilisation and sexual reproduction. Pollen grains transport the male gametes to where the female gamete are contained within the carpel; in gymnosperms the pollen is directly applied to the ovule itself...

, and other factors necessary to increasing crop productivity. Companion planting is a form of polyculture
Polyculture
Polyculture is agriculture using multiple crops in the same space, in imitation of the diversity of natural ecosystems, and avoiding large stands of single crops, or monoculture...

.

Companion planting is used by farmers and gardeners in both industrialized and developing countries for many reasons. Many of the modern principles of companion planting were present many centuries ago in cottage garden
Cottage garden
The cottage garden is a distinct style of garden that uses an informal design, traditional materials, dense plantings, and a mixture of ornamental and edible plants. English in origin, the cottage garden depends on grace and charm rather than grandeur and formal structure...

s in England and home gardens in Asia.

For farmers using an integrated pest management
Integrated Pest Management
Integrated pest management is an ecological approach to agricultural pest control that integrates pesticides/herbicides into a management system incorporating a range of practices for economic control of a pest...

 system, increased yield and/or reduction of pesticides is the goal. For gardeners, the combinations of plants also make for a more varied, attractive vegetable garden, as well as allowing more productive use of space.

History


In China, the mosquito fern has been used for at least one thousand years, as a companion plant for rice
Rice
Rice is the seed of the monocot plants Oryza sativa or Oryza glaberrima . As a cereal grain, it is the most important staple food for a large part of the world's human population, especially in East Asia, Southeast Asia, South Asia, the Middle East, and the West Indies...

 crops. It hosts a special cyanobacteria that fixes nitrogen from the atmosphere, and also blocks out light from getting to any competing plants, aside from the rice, which is planted when tall enough to stick out of the water above the azolla layer.

Companion planting was practiced in various forms by Native Americans
Indigenous peoples of the Americas
The indigenous peoples of the Americas are the pre-Columbian inhabitants of North and South America, their descendants and other ethnic groups who are identified with those peoples. Indigenous peoples are known in Canada as Aboriginal peoples, and in the United States as Native Americans...

 prior to the arrival of Europeans. One common system was the planting of corn
Maize
Maize known in many English-speaking countries as corn or mielie/mealie, is a grain domesticated by indigenous peoples in Mesoamerica in prehistoric times. The leafy stalk produces ears which contain seeds called kernels. Though technically a grain, maize kernels are used in cooking as a vegetable...

 (maize) and pole beans together. The cornstalk would serve as a trellis for the beans to climb while the beans would fix nitrogen
Nitrogen fixation
Nitrogen fixation is the natural process, either biological or abiotic, by which nitrogen in the atmosphere is converted into ammonia . This process is essential for life because fixed nitrogen is required to biosynthesize the basic building blocks of life, e.g., nucleotides for DNA and RNA and...

 for the corn. The inclusion of squash with these two plants completes the Three Sisters
Three Sisters (agriculture)
The Three Sisters are the three main agricultural crops of various Native American groups in North America: squash, maize, and climbing beans ....

 technique, pioneered by Native American peoples.

Companion planting was widely touted in the 1970s as part of the organic gardening
Organic horticulture
Organic horticulture is the science and art of growing fruits, vegetables, flowers, or ornamental plants by following the essential principles of organic agriculture in soil building and conservation, pest management, and heirloom variety preservation....

 movement. It was encouraged for pragmatic reasons, such as natural trellising, but mainly with the idea that different species of plant may thrive more when close together. It is also a technique frequently used in permaculture
Permaculture
Permaculture is an approach to designing human settlements and agricultural systems that is modeled on the relationships found in nature. It is based on the ecology of how things interrelate rather than on the strictly biological concerns that form the foundation of modern agriculture...

, together with mulch
Mulch
In agriculture and gardening, is a protective cover placed over the soil to retain moisture, reduce erosion, provide nutrients, and suppress weed growth and seed germination. Mulching in gardens and landscaping mimics the leaf cover that is found on forest floors....

ing, polyculture
Polyculture
Polyculture is agriculture using multiple crops in the same space, in imitation of the diversity of natural ecosystems, and avoiding large stands of single crops, or monoculture...

, and changing of crops
Intercropping
Intercropping is the practice of growing two or more crops in proximity. The most common goal of intercropping is to produce a greater yield on a given piece of land by making use of resources that would otherwise not be utilized by a single crop. Careful planning is required, taking into account...

.

Examples of companion plants


Nasturtium are well-known to attract caterpillar
Caterpillar
Caterpillars are the larval form of members of the order Lepidoptera . They are mostly herbivorous in food habit, although some species are insectivorous. Caterpillars are voracious feeders and many of them are considered to be pests in agriculture...

s, therefore, planting them around vegetables such as lettuce or cabbage protects them from damage, as egg-laying insects will tend to prefer the nasturtium. This practice is called trap crop
Trap crop
A trap crop is a plant that attracts agricultural pests, usually insects, away from nearby crops. This form of companion planting can save the main crop from decimation by pests without the potential issues and controversy involved in using pesticides....

ping.

Marigold
Tagetes
Tagetes is a genus of 56 species of annual and perennial mostly herbaceous plants in the sunflower family . The genus is native to North and South America, but some species have become naturalized around the world. One species, T...

s assist crops suffering from aphid
Aphid
Aphids, also known as plant lice and in Britain and the Commonwealth as greenflies, blackflies or whiteflies, are small sap sucking insects, and members of the superfamily Aphidoidea. Aphids are among the most destructive insect pests on cultivated plants in temperate regions...

s (greenfly
Greenfly
Greenfly is the artist name of Lawrence Green, a drum and bass music producer and DJ from Reading, England. His music style leans towards the more soul/funk influenced styles of drum'n'bass. He is currently signed to and has been releasing music since 2001...

 among others) through their smell deterring to aphids and attracting hoverflies
Hoverfly
Hoverflies, sometimes called flower flies or syrphid flies, make up the insect family Syrphidae. As their common name suggests, they are often seen hovering or nectaring at flowers; the adults of many species feed mainly on nectar and pollen, while the larvae eat a wide range of foods...

 (a predator of aphids).

Versions


There are a number of systems and ideas using companion planting.

Square foot gardening
Square foot gardening
Square Foot Gardening is the practice of planning small but intensively planted gardens. The phrase "square foot gardening" was popularized by Mel Bartholomew in a 1981 Rodale Press book and subsequent PBS television series. A full-length companion DVD, Square Foot Gardening , was recently released...

, for example, attempts to protect plants from many normal gardening problems by packing them as closely together as possible, which is facilitated by using companion plants, which can be closer together than normal.

Another system using companion planting is the forest garden
Forest gardening
Forest gardening is a food production and agroforestry system based on woodland ecosystems, incorporating fruit and nut trees, shrubs, herbs, vines and perennial vegetables which have yields directly useful to humans...

, where companion plants are intermingled to create an actual ecosystem, emulating the interaction of up to seven levels of plants in a forest or woodland
Woodland
Ecologically, a woodland is a low-density forest forming open habitats with plenty of sunlight and limited shade. Woodlands may support an understory of shrubs and herbaceous plants including grasses. Woodland may form a transition to shrubland under drier conditions or during early stages of...

.

Organic gardening
Organic horticulture
Organic horticulture is the science and art of growing fruits, vegetables, flowers, or ornamental plants by following the essential principles of organic agriculture in soil building and conservation, pest management, and heirloom variety preservation....

 often depends on companion planting for its best performance, since so many synthetic means of fertilizing, weed reduction, pest control, and other garden needs are forbidden.

Good weeds


There are many beneficial weed
Beneficial weed
|thumb|right|Clover was once included in grass seed mixes, because of its great benefits to yard healthA beneficial weed is any of various plants not generally considered domesticated, but which nonetheless has some companion plant effect, or else is edible or somehow beneficial...

s, which can be allowed to grow alongside plants, imparting the same kinds of benefits as mixing cultivated crops.

Host-finding disruption


Recent studies on host-plant finding have shown that flying pests are far less successful if their host-plants are surrounded by any other plant or even "decoy-plants" made of green plastic, cardboard, or any other green material.

The host-plant finding process occurs in phases:
  • The first phase is stimulation by odours characteristic to the host-plant. This induces the insect to try to land on the plant it seeks. But insects avoid landing on brown (bare) soil. So if only the host-plant is present, the insects will quasi-systematically find it by simply landing on the only green thing around. This is called (from the point of view of the insect) "appropriate landing". When it does an "inappropriate landing", it flies off to any other nearby patch of green. It eventually leaves the area if there are too many 'inappropriate' landings.
  • The second phase of host-plant finding is for the insect to make short flights from leaf to leaf to assess the plant's overall suitability. The number of leaf-to-leaf flights varies according to the insect species and to the host-plant stimulus received from each leaf. The insect must accumulate sufficient stimuli from the host-plant to lay eggs; so it must make a certain number of consecutive 'appropriate' landings. Hence if it makes an 'inappropriate landing', the assessment of that plant is negative, and the insect must start the process anew.


Thus it was shown that clover
Clover
Clover , or trefoil, is a genus of about 300 species of plants in the leguminous pea family Fabaceae. The genus has a cosmopolitan distribution; the highest diversity is found in the temperate Northern Hemisphere, but many species also occur in South America and Africa, including at high altitudes...

 used as a ground cover had the same disruptive effect on eight pest species from four different insect orders. An experiment showed that 36% of cabbage root flies laid eggs beside cabbages growing in bare soil (which resulted in no crop), compared to only 7% beside cabbages growing in clover (which allowed a good crop). Simple decoys made of green cardboard also disrupted appropriate landings just as well as did the live ground cover.

Companion plant categories


Companion plants can benefit each other in a number of different ways, including:
  • Flavor enhancement — some plants, especially herbs, seem to subtly change the flavor of other plants around them.
  • Hedged investment — multiple plants in the same space increase the odds of some yield being given, even if one category encounters catastrophic issues
  • Increased level interaction — plants that grow on different levels in the same space, perhaps providing ground cover or working as a trellis for another plant
  • Nitrogen fixation
    Nitrogen fixation
    Nitrogen fixation is the natural process, either biological or abiotic, by which nitrogen in the atmosphere is converted into ammonia . This process is essential for life because fixed nitrogen is required to biosynthesize the basic building blocks of life, e.g., nucleotides for DNA and RNA and...

    — plants that fix nitrogen in the ground, making it available to other plants
  • Pest suppression — repelling pest insects, weeds, nematodes, or pathogenic fungi, through chemical means .
  • Pollinator and predator recruitment — The use of plants that produce copious nectar and protein-rich pollen
    Pollen
    Pollen is a fine to coarse powder containing the microgametophytes of seed plants, which produce the male gametes . Pollen grains have a hard coat that protects the sperm cells during the process of their movement from the stamens to the pistil of flowering plants or from the male cone to the...

     in a vegetable garden (insectary plants
    Insectary plants
    Insectary plants is a term used to describe plants that attract insects. As such, beneficial insectary plants are intentionally introduced into an ecosystem to increase pollen resources and nectar resources required by the natural enemies of harmful or unwanted insect pests...

    ) is a good way to recruit higher populations of beneficial insects that control pests. Some insects in the adult form are nectar or pollen feeders, while in the larval form they are voracious predators of pest insects.
  • Positive hosting — attracts or is inhabited by beneficial insects or other organisms which benefit plants, as with ladybugs or some "good nematodes".
  • Protective shelter — one type of plant may serve as a wind break or shade for another
  • Trap crop
    Trap crop
    A trap crop is a plant that attracts agricultural pests, usually insects, away from nearby crops. This form of companion planting can save the main crop from decimation by pests without the potential issues and controversy involved in using pesticides....

    ping
    — plants that attract pests away from others
  • Pattern disruption — in a monoculture
    Monoculture
    Monoculture is the agricultural practice of producing or growing one single crop over a wide area. It is also known as a way of farming practice of growing large stands of a single species. It is widely used in modern industrial agriculture and its implementation has allowed for large harvests from...

    , pest spread from one plant to the next, is interrupted by companion plants.

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