Certain plants know how to help their neighbors

part 14: Companion planting

Companion planting is a

method of arranging your

plantings according to which

types of plants are potentially

beneficial to one another.

Companion planting may

reduce competition for water

and nutrients, decrease pest

and disease problems, and

possibly increase vegetable

production.

Companion planting is

thought to work, in part,

because it increases plant

diversity. Imagine a hungry

insect population finding its

way into your garden. If it

encounters an entire row of

its preferred food, you can

bet that the entire row will be

decimated before you even

notice. However, what if that

insect population found one

plant of its favorite food, only

to be halted from moving

onto the next one because

there’s a plant it doesn’t like in

its way? You would probably

notice the damage and might

be able to control the problem

before losing your entire crop.

And, the insects may move

on to “greener pastures” if

undesirable plants are mixed

in with desirable ones.

In its simplest form,

companion planting is

alternating two types of

vegetables in a single row.

This is sometimes called

intercropping, and alternating

garlic or basil with tomato

plants is a popular example.

You can also intercrop more

than two varieties. A classic

multispecies intercropping

example is growing onions,

lettuce and carrots together.

Each of these plants grows its

Increasing the diversity of your garden can save your plants from pests and competition

By Leslie Allen n Horticulture Program Coordinator

INTERCROPPING: Fancy terms are used these days, but Native Americans had an example called the Three Sisters garden.

The University of Nevada, Reno is an Equal Opportunity/ Affirmative Action employer and does not discriminate on the basis of race, color, religion, sex, age, creed, national origin, veteran status, physical or mental disability, or sexual orientation in any program or activity it conducts. The University of Nevada employs only United States citizens and aliens lawfully authorized to work in the United States.

Copyright © 2009 University of Nevada Cooperative Extension

Continued on back

About this seriesThis article is the 14th in a University of Nevada Cooperative Extension series on starting your own vegetable garden. Articles explore such topics as site selection, ordering seeds and preparing your soil. To find the complete series of articles, go to our “Grow Your Own” page at www.unce.unr.edu

In a Three Sisters Garden (above), the corn provides a living trellis for the pole beans, the pole beans provide nitrogen for use by the corn, and the squash provides living mulch. (Jim Sloan photo)

roots at different levels in the

soil, so they don’t compete

with each other for nutrients.

Aboveground, these plants

have such distinct growth

habits and foliage shapes that

they don’t crowd each other

for sunlight or space.

Bush beans and peas

are popular vegetables to

intercrop with plants that are

heavy nitrogen feeders. This

is because beans and peas

are nitrogen fixers, meaning

they can utilize atmospheric

nitrogen for their growth

and reproduction. They have

symbiotic bacteria that live on

their roots and form nodules

rich in nitrogen. Plants growing

near them will be able to

intertwine their roots with the

beans’ roots and utilize the

nitrogen stored there.

An ancient and popular

companion planting is the

Three Sisters garden. The

Three Sisters method is a

unique Native American way

of growing corn, pole bean,

and squash. These three

plants mutually benefit each

other as they grow. The corn

provides a living trellis for the

pole beans, the

pole beans provide

nitrogen for use by

the corn, and the

squash provides

living mulch. The

three plants create

a synergy that

produces a greater

yield, increased

nutrition and

more food calories

than if only one

of the crops was

grown alone in the

same space. The

Anasazi added another sister,

bee plant, Cleome serrulata,

to the plant mix to improve

pollination of the beans and

squash and provide pollen to

the bees.

The Anasazi knew that

flowering plants are great

additions to vegetable

gardens, as many of them

attract beneficial insects.

For example, cosmos attract

syrphid flies, lacewings

and tiny parasitic wasps.

All of these insects help

control pests such as aphids,

leafhoppers, spider mites and

cutworms.

Our farming forefathers also

knew the value of planting

flowers near their vegetables.

They planted “insectary”

gardens to attract beneficial

insects to the farm. You, too,

can plant an insectary garden

within your vegetable garden.

Try edging your garden with

annual or perennial herbs and

flowers. You can harvest the

herbs as needed, but their

real value is in the flower. Dill,

parsley and cilantro flowers

attract many beneficial insects.

When you’re designing

your garden this year, mimic

how Mother Nature designs

gardens. Think of hiking

through a beautiful meadow

in the Sierra Nevada at the

height of wildflower season.

You don’t see row upon row

of one type of flower. Rather,

you see a multicolored carpet

of many different types of

flowers. Many of the flowers

bloom at different times and

grow to different heights; and

when they die, they open up

new spaces for another plant

species to grow. You can follow

these same principles when

designing your garden.

About the author

Leslie Allen is the

former commercial

horticulture program

coordinator for the

western area of

University of Nevada

Cooperative Extension.

She is also a 2008

Nevada EcoNet Golden

Pine Cone award

recipient.

Companions

Try edging your garden with annual or perennial herbs and flowers. (Jim Sloan photo)

Popular companions Companion planting has its roots in both science and folklore. Some people swear by planting basil with their tomatoes, and others won’t plant basil without garlic.

Here are some suggestions for popular homegrown vegetables. If you would like to read more about companion planting, “Carrots Love Tomatoes,” by Louise Riotte, and “Gaia’s Garden,” by Toby Hemenway, are a couple of books that have comprehensive plant lists and design suggestions.

Of course, you can also always call us, (775) 784-4848, or visit us at University of Nevada Cooperative Extension for recommendations and more information.

Vegetable Companion

Tomatoes and peppers Asparagus, carrots, chives, cucumbers, garlic, marigold, nasturtium, onions, parsley, peppers, basil

Potatoes Watermelon, beans, broccoli, cabbage, corn, peas

Strawberries Spinach, lettuce, bush beans, borage, and apple, pear and peach trees

Cucumbers Corn, beans, peas, radishes, sunflowers