permaculture

[Lawrence London <lfljvenaura@gmail.com>]

Companion plants
http://eap.mcgill.ca/publications/EAP55.htm

*EAP Publications <http://eap.mcgill.ca/General/eap_ind.htm> *| *Virtual
Library <http://eap.mcgill.ca/General/library.htm>* | *Magazine Rack
<http://eap.mcgill.ca/General/magazine.htm>* | *Search
<http://eap.mcgill.ca/Search/search.htm>*
<http://eap.mcgill.ca/disc1_frm.htm>

<http://eap.mcgill.ca/disc1_frm.htm>* Join the Ecological  Solutions
Roundtable <http://eap.mcgill.ca/disc1_frm.htm>*
------------------------------


Companion plants

by Professor Stuart B. Hill Department of Entomology Macdonald College

"Do you really believe that you can earn $6,000 a year growing vegetables
on just a fifth of an acre?'' one of my colleagues asked me. He was
referring to a booklet describing the work of a group of vegetable
producers in Santa Cruz, California (Jeavons, 1974).

"Sure," I replied. I had never met them but I had corresponded with them
and read their publications, and I had no reason to doubt their claims. I
tried to explain that they were using the biodynamic/French intensive
method of production, which really only boiled down to the use of raised
beds to increase air supply to the roots, and companion planting. The
raised beds he could understand but the companion planting left him cold.

Now, if they had been applying synthetic fertilizers, herbicides, and
insecticides, it might not have been so difficult for him to comprehend,
but they would never let these things anywhere near their gardens. No, they
did it instead with companion plants, plus a little compost. While most of
us know something of the benefits of well-made compost, few of us are
familiar with the advantages and techniques of companion planting. It
involves nothing more than arranging the plants in a garden in such a way
that they enhance the growth and quality of nearby crops (or, at least, do
not antagonize them), provide maximum ground cover, and, if possible,
improve the soil.

This approach has much to recommend it. More can be grown per area, and the
soil is protected from erosion by wind and rain. The only problem is that
it involves more care when planning, seeding or planting, cultivating and
harvesting.

While it is rarely known exactly how the plants benefit one another, some
generalization can be made. ''Companions" often include plants with
contrasting properties: sun-loving and shade-loving ones; plants with deep
roots and those with shallow roots; slow-growing and fast-growing plants;
heavy feeders and light feeders or crops that incorporate nitrogen into the
soil; aromatic plants, which often repel pests, and non-aromatic ones. ones
with early flowers that provide pollen and nectar for some insect predators
and parasitoids (insects that parasitize insects), and plants that do not
bear flowers until late in the season (or that are not allowed to flower);
plants that are more attractive to a particular pest than another, i.e. as
a trap-crop; and plants that stimulate biological activity in the soil with
crops that are heavy feeders.

Some of the relationships probably involve the release of chemical exudates
from the roots, which may have a direct effect on other plants or an
indirect effect via other organisms in the soil. It may also involve the
release of certain gases or odours, which repel pests, from either the
roots or the aerial parts of the plant. While the processes involved are
difficult to demonstrate, the late Dr. Ehrenfried E. Pfeiffer and Dr. Erica
Sabarth of the Bio-Dynamic Association have shown that by adding the juices
of pairs of plants to a five per cent copper chloride solution and allowing
it to crystallize slowly on a glass plate they were able to predict which
plants would be companionate and which antagonistic, based on the
appearance of the crystallization patterns or chromatograms. Today they use
paper chromatography techniques. Their findings, together with trial and
error experiences of numerous gardeners, have been summarized in a pamphlet
by Richard Gregg (1943) and in a book entitled Companion Plants and How to
Use Them.

Tables 1 and 2 are based largely on these publications. These lists should
be used as a basis for experimentation rather than as a guarantee of
success. It is particularly important to experiment with the ratios in
which to mix plants and the spacings to use between them. For example, bush
beans are found to be most beneficial to celery in the ratio of one bean
plant to six of celery, and to cucumbers when they are planted around the
cucumber patch. Sometimes seeds may be mixed together, as with lettuce,
carrots and radish, or they may be grown in adjacent patches, or as a
zig-zag with the companion plants in between the zigs (and the zags)!

My first contact with companion plants was when I was four or five and I
walked into a patch of stinging nettles. My father grabbed some leaves of
dock, which always seem to grow nearby, and rubbed the juice of the leaves
on my stings and the itching soon subsided. But stinging nettles have their
value too. Grown near the aromatic herbs they are said to increase the
aromatic oils in these plants by up to 80 per cent; and like foxglove and
lilly-of-the-valley, they improve the keeping quality of plants that they
are grown near, particularly tomato.

Other beneficial plants to have around the vegetable garden are wild rose,
elderberry, buddleia, privet, golden rod, and mustard.

While companion planting is a lot of fun and makes the vegetable garden
more attractive, both to the eye and to the nose, it has a more serious
side. It represents an effort on the part of some producers to manage
agricultural systems according to principles that can be gained by studying
natural systems. The absence of monocultures in nature prompts the
question,'''are we directing our effort in the wrong direction by
developing technologies to maintain such systems when perhaps we could be
developing them to maintain mixed crop systems?"

References

Gregg, R. B. 1943. Companion and Protective Plants. Bio-Dynamics 3(1),
1-10.

Heckel, A.. (Ed.) 1967. The Pfeiffer Garden Book; Bio-Dynamics in the Home
Garden Bio-Dynamic Farming & Gardening Association Inc., Stroudsburg, Penn.

Hylton, William H. (Ed.) 1974. The Rodale Herb Rook. Rodale Press Book
Division Emmaus, Pa. 18049

Jeavons, J. 1974. How to Grow More Vegetables Than You Ever Thought
Possible on Less Land Than You Can Imagine. Ecology Action of the
Midpeninsula 2225 El Camino Real, Palo Alto, California 94306, U.S.A.

Philbrick, H. and Gregg, R. B. 1966. Companion Plants and How to Use Them.
The Devin-Adair Co., N.Y.

Tompkins, P. and Bird, C. 1973. The Secret Life of Plants. Avon Books, N.Y.

Copyright © 1975 *Ecological Agriculture Projects*