Companion planting involves arranging plants together that are potentially beneficial to one another. This can reduce competition for resources and pests. A classic example is the Three Sisters garden of corn, beans, and squash which provide mutual benefits. Companion planting increases plant diversity, which can confuse pests and attract beneficial insects. Popular companions include basil with tomatoes, and onions, lettuce, and carrots which have distinct growth habits and don't compete for space.

1. pa rt 14: C o m pa n i o n P l a n t i n g
Certain plants know how
to help their neighbors
Increasing the diversity of your garden can save your
plants from pests and competition
About this series
By Leslie Allen n Horticulture Program Coordinator This article is the 14th in
a University of Nevada
INTERCROPPING: Fancy terms are used these days, but Native Americans had an Cooperative Extension series
example called the Three Sisters garden. on starting your own vegetable
garden. Articles explore such
Companion planting is a topics as site selection, ordering
method of arranging your seeds and preparing your soil.
plantings according to which To find the complete series of
types of plants are potentially articles, go to our “Grow Your
beneficial to one another. Own” page at www.unce.unr.
Companion planting may edu
reduce competition for water
and nutrients, decrease pest
and disease problems, and
possibly increase vegetable
production.
Companion planting is In a Three Sisters Garden (above), the corn provides a living trellis for the pole
thought to work, in part, beans, the pole beans provide nitrogen for use by the corn, and the squash
provides living mulch. (Jim Sloan photo)
because it increases plant
diversity. Imagine a hungry there’s a plant it doesn’t like in vegetables in a single row.
insect population finding its its way? You would probably This is sometimes called
way into your garden. If it notice the damage and might intercropping, and alternating
encounters an entire row of be able to control the problem garlic or basil with tomato
its preferred food, you can before losing your entire crop. plants is a popular example.
bet that the entire row will be And, the insects may move You can also intercrop more
decimated before you even on to “greener pastures” if than two varieties. A classic
notice. However, what if that undesirable plants are mixed multispecies intercropping
insect population found one in with desirable ones. example is growing onions,
plant of its favorite food, only In its simplest form, lettuce and carrots together.
to be halted from moving companion planting is Each of these plants grows its
onto the next one because alternating two types of Continued on back
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Copyright © 2009 University of Nevada Cooperative Extension

2. Companions pole beans, the Popular companions
pole beans provide Companion planting has its roots
roots at different levels in the nitrogen for use by in both science and folklore. Some
soil, so they don’t compete the corn, and the people swear by planting basil with
with each other for nutrients. squash provides their tomatoes, and others won’t
Aboveground, these plants living mulch. The plant basil without garlic.
have such distinct growth three plants create
habits and foliage shapes that a synergy that Here are some suggestions for
they don’t crowd each other produces a greater popular homegrown vegetables. If
for sunlight or space. yield, increased you would like to read more about
Bush beans and peas nutrition and companion planting, “Carrots
are popular vegetables to more food calories Love Tomatoes,” by Louise Riotte,
intercrop with plants that are than if only one and “Gaia’s Garden,” by Toby
heavy nitrogen feeders. This of the crops was Hemenway, are a couple of books
is because beans and peas grown alone in the Try edging your garden with annual or perennial herbs that have comprehensive plant
and flowers. (Jim Sloan photo)
are nitrogen fixers, meaning same space. The lists and design suggestions.
they can utilize atmospheric Anasazi added another sister, flowers near their vegetables.
nitrogen for their growth bee plant, Cleome serrulata, They planted “insectary” Of course, you can also always
and reproduction. They have to the plant mix to improve gardens to attract beneficial call us, (775) 784-4848, or
symbiotic bacteria that live on pollination of the beans and insects to the farm. You, too, visit us at University of Nevada
their roots and form nodules squash and provide pollen to can plant an insectary garden Cooperative Extension for
rich in nitrogen. Plants growing the bees. within your vegetable garden. recommendations and more
near them will be able to The Anasazi knew that Try edging your garden with information.
intertwine their roots with the flowering plants are great annual or perennial herbs and
beans’ roots and utilize the additions to vegetable flowers. You can harvest the
nitrogen stored there. gardens, as many of them herbs as needed, but their
An ancient and popular attract beneficial insects. real value is in the flower. Dill,
companion planting is the For example, cosmos attract parsley and cilantro flowers
Three Sisters garden. The syrphid flies, lacewings attract many beneficial insects.
Three Sisters method is a and tiny parasitic wasps. When you’re designing
unique Native American way All of these insects help your garden this year, mimic
of growing corn, pole bean, control pests such as aphids, how Mother Nature designs
and squash. These three leafhoppers, spider mites and gardens. Think of hiking
plants mutually benefit each cutworms. through a beautiful meadow
About the author
other as they grow. The corn Our farming forefathers also in the Sierra Nevada at the
provides a living trellis for the knew the value of planting height of wildflower season. Leslie Allen is the
You don’t see row upon row former commercial
Vegetable Companion
of one type of flower. Rather, horticulture program
Tomatoes and peppers Asparagus, carrots, chives, you see a multicolored carpet coordinator for the
cucumbers, garlic, marigold,
nasturtium, onions, parsley, peppers, of many different types of western area of
basil flowers. Many of the flowers University of Nevada
Potatoes Watermelon, beans, broccoli, bloom at different times and Cooperative Extension.
cabbage, corn, peas grow to different heights; and She is also a 2008
when they die, they open up Nevada EcoNet Golden
Strawberries Spinach, lettuce, bush beans,
borage, and apple, pear and peach new spaces for another plant Pine Cone award
trees species to grow. You can follow recipient.
Cucumbers Corn, beans, peas, radishes, these same principles when
sunflowers
designing your garden.