Companion Planting:
Basic Concept and Resources
Research & compiled by Camille LeblancResearch & compiled by Camille Leblanc
While companion planting has a long history, the mechanisms of beneficial plant interaction have not
always been well overstood. Traditional recommendations used by gardeners have evolved from
an interesting combination of historical observation, horticultural science, and a few unconventional sources.
Companion planting can be described as the establishment of two or more plant species in close proximity so that some cultural benefit (pest control, higher yield, etc.) is derived. The concept embraces a number of strategies that increase the biodiversity of agro ecosystems.
Traditional Companion Planting
Table 1. COMPANION PLANTING CHART FOR HOME & MARKET GARDENING (compiled from traditional literature on companion planting)
CROP COMPANIONS INCOMPATIBLE
Asparagus Tomato, Parsley, Basil
Beans Most Vegetables & Herbs
Beans, Bush Irish Potato, Cucumber, Corn, Strawberry, Celery, Summer Savoury
Onion
Beans, Pole Corn, Summer Savoury, Radish
Onion, Beets, Kohlrabi, Sunflower
Cabbage Family
Aromatic Herbs, Celery, Beets, Onion Family, Chamomile, Spinach, Chard
Dill, Strawberries, Pole Beans, Tomato
Carrots English Pea, Lettuce, Rosemary, Onion Family, Sage, Tomato
Dill
Celery Onion & Cabbage Families, Tomato, Bush Beans, Nasturtium
Corn Irish Potato, Beans, English Pea, Pumpkin, Cucumber, Squash
Tomato
Cucumber Beans, Corn, English Pea, Sunflowers, Radish
Irish Potato, Aromatic Herbs
Eggplant Beans, Marigold
Lettuce Carrot, Radish, Strawberry, Cucumber
Onion Family Beets, Carrot, Lettuce, Cabbage Family, Summer Savory
Beans, English Peas
Parsley Tomato, Asparagus
Pea, English Carrots, Radish, Turnip, Cucumber, Corn, Beans
Onion Family, Gladiolus, Irish Potato
Potato, Irish Beans, Corn, Cabbage Family, Marigolds, Horseradish
Pumpkin, Squash, Tomato, Cucumber, Sunflower
Pumpkins Corn, Marigold Irish Potato
Radish English Pea, Nasturtium, Lettuce, Cucumber
Hyssop
Spinach Strawberry, Faba Bean
Squash Nasturtium, Corn, Marigold Irish Potato
Tomato Onion Family, Nasturtium, Marigold, Asparagus, Carrot, Parsley, Cucumber
Irish Potato, Fennel, Cabbage Family
Turnip English Pea Irish Potato
Trap Cropping
Sometimes, a neighbouring crop may be selected because it is more attractive to pests
and serves to distract them from the main crop. An excellent example of this is the use of collards to draw the diamond back moth
away from cabbage.
Symbiotic Nitrogen FixationLegumes such as peas, beans, and clover have the ability to fix atmospheric nitrogen for their
own use and for the benefit of neighbouring plants via symbiotic relationship with
Rhizobium bacteria. Forage legumes, for example, are commonly seeded with grasses to
reduce the need for nitrogen fertilizer. Likewise, beans are sometimes interplanted with corn.
Biochemical Pest SuppressionSome plants exude chemicals from roots or aerial parts that suppress or repel pests and protect neighbouring plants. The African marigold, for example, releases thiopene—a nematode repellent—making it a good
companion for a number of garden crops. The manufacture and release of certain biochemical's is also a
factor in plant antagonism. Allelochemicals such as juglone—found in black walnut—suppress the growth of
a wide range of other plants, which often creates a problem in home horticulture. A positive use of plant
allelopathy is the use of mow-killed grain rye as a mulch. The allelochemicals that leach from rye residue prevent
weed germination but do not harm transplanted tomatoes, broccoli, or many other vegetables.
bi·o·chem·i·cal relating to biochemistry: relating to the chemical substances present in living organisms and the reactions and methods used to identify or characterize
an·tag·o·nism 1. hostility: hostility or hatred causing opposition and ill will 3. physiology neutralizing interaction: the interaction between two or more chemical substances
that diminishes the effect each of them has individually
al·le·lo·chem·i·cal toxic plant chemical: a chemical produced by one plant that is toxic to another. Also called allelotoxin
al·le·lop·a·thy suppression of neighboring plants: the release into the environment by one plant of a substance
that inhibits the germination or growth of other potential competitor plants of the same or another species
Physical Spatial Interactions
For example, tall-growing, sun-loving plants may share space with lower-growing, shade-tolerant
species, resulting in higher total yields from the land. Spatial interaction can also yield pest control
benefits. The diverse canopy resulting when corn is companion-planted with squash or pumpkins is
believed to disorient the adult squash vine borer and protect the vining crop from this damaging pest. In
turn, the presence of the prickly vines is said to discourage rodents from ravaging the sweet corn.
Nurse Cropping
Tall or dense-canopied plants may protect more vulnerable species through shading or by
providing a windbreak. Nurse crops such as oats have long been used to help establish alfalfa and
other forages by supplanting the more competitive weeds that would otherwise grow in their place. In many instances, nurse cropping is
simply another form of physical-spatial
interaction. al·fal·fa forage crop: a European and Asian plant in the pea family, widely grown as a hay and
forage crop.
oat grass with edible seed: a grass that has edible seeds and is grown in numerous northern countries as a cereal crop
spa·tial relating to space: relating to, occupying, or happening in space
Beneficial Habitats
Beneficial habitats—sometimes called refugia—are another type of companion plant interaction that has drawn considerable attention in recent years. The benefit is derived when companion plants provide a
desirable environment for beneficial insects and other arthropods especially those predatory and parasitic species which help to keep pest
populations in check. Predators include ladybird beetles, lacewings hover flies, mantids, robber flies, and non-insects such as spiders and
predatory mites. Parasites include a wide range of fly and wasp species including tachinid flies, and Trichogramma and ichneumonid wasps.
Agro ecologists believe that by developing systems to include habitats that draw and sustain beneficial insects, the twin objectives of reducing
both pest damage and pesticide use can be attained. For detailed information on establishing beneficial habitats, request the ATTRA
publication Farmscaping to Enhance Biological Control.ar·thro·pod
invertebrate animal: an invertebrate animal that has jointed limbs, a segmented body, and an exoskeleton made of chitin. Insects, arachnids, centipedes, and crustaceans are arthropods.
Security Through DiversityA more general mixing of various crops and varieties provides a degree of security to the grower. If pests or adverse conditions reduce
or destroy a single crop or cultivar, others remain to produce some level of yield.
Furthermore, the simple mixing of cultivars, as demonstrated with broccoli in University
of California research, can reduce aphid infestation in a crop.
COMPANION VEGETABLE GARDENING
It's said that vegetables are like people, they thrive on companionship. It is believed that vegetables will yield up to twice as much when they are surrounded
with companion plants. So in this article we will discuss the top 12 vegetables and their best friends.
If you're getting ready to plant your vegetable garden you may want to try placing the various vegetable crops so you can take advantage of their natural
friends. If you have already planted your vegetable garden you may want to make some changes in
subsequent plantings later this summer.
The following are a list of the top 12 vegetables and their ideal
planting companions.
Beans--they like celery and cucumbers but dislike onions and fennel. Beets--Bush beans, lettuce, onions, kohlrabi, and most members of the cabbage family are companion plants. Keep the pole beans and mustard away from them. Cabbage--Celery, dill, onions and potatoes are good companion plants They dislike strawberries, tomatoes, and pole beans. Carrots--Leaf lettuce, radish, onions and tomatoes are their friends, Plant dill at the opposite end of the garden. Corn--Pumpkins, peas, beans, cucumbers and potatoes are nice companion plants, Keep the tomatoes away from them. Cucumbers--They like corn, peas, radishes, beans and sunflowers. Cucumbers dislike aromatic herbs and potatoes so keep them away.
Lettuce--It grows especially well with onions. Strawberries carrots, radishes and cucumbers also are friends and good companion plants. Onions--Plant them near lettuce, beets, strawberries and tomatoes but keep them away from peas and beans. Peas--Carrots, cucumbers, corn, turnips and radishes plus beans, potatoes and aromatic herbs are their friends. Keep the peas away from onions, garlic, leek, and shallots
Radishes--This is one vegetable that has a lot of friends, they are excellent companion plants with
beets, carrots, spinach and parsnips. Radishes grow well with cucumbers and beans. It's said that summer
planting near leaf lettuce makes the radishes more tender. Avoid planting radishes near cabbage,
cauliflower, Brussels sprouts, broccoli, kohlrabi or turnips.
Squash--Icicle radishes, cucumbers and corn are among their friends.
Tomatoes--Carrots, onions and parsley are good companion plants. Keep the cabbage and cauliflower
away from them.
Sometimes plant friendships are one-sided. Carrots are said to help beans, but beans don’t reciprocate. Though beans will
help nearby cucumbers. Other plants have bad companions and you'll be doing them a
favour to keep them apart. Beans and onions are natural enemies so keep them at opposite sides of the garden.
If you have a patio you might try mint to repel ants, and basil to keep the flies and mosquitoes away. Both herbs have pretty flowers and are fragrant too. Besides, they're nice to harvest and use in the kitchen. "Carrots Love Tomatoes" getting to know good and bad companions can double the bounty of
your garden. The only required work is to plan your garden planting properly.
Herb Companion Chart
The idea that herbs make good companion plants is not new. Some of the earliest written documents on
gardening discuss these relationships. When selecting your companion plants you will need to consider more than which pests are deterred. Think about what each plant adds or takes away from the soil and what effect the proximity of strong herbs may have on the flavour
of your vegetables. Try to avoid placing two heavy feeders or two shallow rooted plant types near each
other.
Herb Companions Pests Repelled
Basil Tomatoes Flies, Mosquitoes
Dead Nettle
Chives Carrots
Potatoes Potato Bug
Dill CabbageDislikes Carrots
Garlic
Fennel Most plants dislike this herb
Roses, Raspberries Japanese Beetle, Aphids
Marigolds Plant throughout the garden Mexican Bean Beetles, Nematodes, others
MintCabbage, Tomatoes
White Cabbage Moth, aphids, flea beetles
Pot Marigold
Tomatoes Tomato Worm, Asparagus Beetles, others
Rosemary Cabbage, Beans Carrots, Sage Cabbage Moth, Bean Beetle, Carrot Fly
SageRosemary, Cabbage, Carrots
Dislikes Cucumbers
Cabbage Moth, Carrot Fly, Flea Beetle, Slugs
Thyme Cabbage Cabbage Worm
Companion planting practices
• The following are some examples of farming in the village of Cochrane where companion planting is practiced traditionally with herbs & vegetables
Herbs & vegetables plot #1
Farmer of plot
Extension Off. Examining plot
Vegetable plot #2
Asparagus & Flowers
Farmer harvesting crop
Compost pit
Farmer harvesting
Companion of cane & marigold
Harvest Time
• We have come to harvest time remember in organic planting always make certain you know what your companion crops are in the field, this will lead to reduce crop damage through pest & diseases.
• Remember organic farming is a process not a past time. Have fun.
Researched & compiled by Camille Researched & compiled by Camille LeblancLeblanc