Introducing Intercropping

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Intercropping, the act of planting different crops together, can be divided into different sub-categories. Mixed intercropping is when a person grows more than two different crops together without any “distinct row arrangement” (Vandermeer 1989). Then, there is row intercropping, usually found in intensive agriculture, where multiple types of plants are grown in rows made by ploughs (ibid.). Strip intercropping is when the gardener keeps the plants on separated strips but close enough to where they are able to agronomically interact with one another (ibid.). Finally, relay intercropping is more focused on the timing and life-cycles of the plants, which could use row intercropping or mixed intercropping alike (ibid.). 

While many gardeners and horticultures disagree on whether intercropping should be called “companion planting”, due to the personification of plants and their relationships with each other and their environment, Tom Maloney, a professor of horticulture at Penn State Extension said, “the theory behind companion planting is that certain plants may help each other take up nutrients, improve pest management, or attract pollinators.” In fact, while some plants that have similar root depths or crowed one another out do not grow at their best when planted in proximity, studies have found that most plant associations are positive and worth a try (almanac.com).

Plants do not just sit passively in their environment. They have unique behaviours and characteristics which change the space around them and influence how other plants grow and how wildlife, such as insects, interact with them. Things like “temperature, soil moisture content, soil pH, solar radiation availability (both in terms of quantity and quality of light), and nutrient availability” are all influenced by plants (Chalker-Scott).

The plant relationships can be extremely valuable and do often work out to allow some plants a better chance at surviving certain conditions (ibid.). For example, some plants have been found to lift water into the upper layers of soil, allowing for more shallow reaching plants to benefit (Lovell 2019). These characteristics are important to think about when planting a garden, especially if in a tighter space. Intercropping can be an extremely useful and exciting tool to make the most of the space you have however and have more successful and bountiful harvests! 

In addition, while it is common for gardeners to create “beds” for each crop, keeping the space ordered, intercropping, mixing in different herbs and plants, can be advantageous to prevent insects from being attracted to and destroying crops – this biodiversity puts extra pheromones into the air, keeping pests from picking up on the specific smells which attract them (MIgardener 2019). In addition, having different crops interspersed among one another helps prevent the soil from being exposed to too much sunlight, water or wind, which can destroy or strip away the important bacteria in the top layer of soil (ibid.). 

Dr. Martin Entz, from the Plant Science department of the University of Manitoba noted, “if you think about how nature works, nature is always intercropping, there’s always more things on the land than just one thing” (Lovell 2019). These relationships shift and change throughout the season, and some plants will benefit and others might not depending on whether or not there is competition for resources (Chalker-Scott). For example, planting crops that have large leaves at the same level might prevent air from flowing, increasing the likeliness for the leaves to develop mildews, fungus, or blight (MIgardener 2019). 

Below, is a starters list of several common crops, their main needs and threats, and the most common plants they are grown with. Feel free to pick and chose your own combinations though, and let us know what has been working for you! 

Crops What they need Natural threats Intercropping plants
Beans Push beans support themselves, while pole beans climb. They have shallow roots, grow well in well-draining but moist soil, and “fix their own nitrogen in the soil.” – this quality makes beans a natural fertilizer Anthracnose

Aphids

Cucumber beetles

Cutworms

Japanese beetles

Mexican bean beetles

Powdery mildew

Slugs

White mould

Whiteflies

Woodchucks

Corn 

Squash

 

 

 

 

*The combination of all three is known as “The Three Sisters”

Carrots Carrots are deep growing crops, which prefer a cooler soil but a lot of sun, and continuous moisture. Black canker

Carrot rust flies

Flea beetles

Root-knot nematodes

Wireworms

Aster yellow disease

Beans

Tomatoes

Sweet Corn Corn has shallower reaching roots and requires a warmer environment, lots of water, and is pollinated with the wind. Cucumber beetles

Flea beetles

cutworms

Cucumber

Melons

Squash

Peas

Beans

Pumpkins

Cucumbers Bush cucumbers support themselves while vining cucumbers climb. These plants need warmth, a lot of sunlight and water Squash bugs

Aphids

Powdery mildew

Cucumber beetles

Beans

Corn

Peas

Cabbage

Lettuce Cool-season plants, so while they need a good amount of sunlight, they can be easily overheated. Need well-draining but moist soil Aphids

Cutworms

Earwigs

Powdery mildew

Lettuce mosaic virus

Slugs and snails

White mould

Woodchucks

Chives

Garlic

Tomatoes

Corn

Melons Melons survive better in warm conditions with a lot of sun and consistent water. They need to be pollinated to produce fruit. Too much nitrogen can reduce the amount of fruit.  Aphid

Cucumber beetles

Squash vine borer moths

Fusarium wilt

Powdery mildew

Corn

Pumpkin

Radish

Squash

Squash Squash has many wide-reaching vines and is often used as a ground cover to help prevent weeds from growing. The plant needs a lot of sunshine and water, and needs to be well pollinated Cucumber beetles

Aphids

Squash vine borer

Powdery mildew

Blossom-end rot

Anthracnose

Corn

Melons

Pumpkins

*Information in table taken from almanac.com and garden.lovetoknow.com

Work Cited

Chalker-Scott, Linda. “The Myth of Companion Plantings.” Washington State University Extension, Horticultural Myths, Washington State University, puyallup.wsu.edu/lcs/.

Cosmato, Donna. “Which Vegetables Grow Well Together.” Home and Garden, LoveToKnow Corp, garden.lovetoknow.com/wiki/Which_Vegetables_Grow_Well_Together.

Lovell, Angela. “The Science behind Intercropping.” Grainews, 17 Apr. 2019, www.grainews.ca/features/the-science-behind-intercropping/. 

Markham, Derek. “32 Companion Plants to Grow With Your Peppers.” Treehugger, 9 Sept. 2020, www.treehugger.com/companion-plants-grow-your-peppers-4858801. 

“Plants You Can Intercrop With Tomatoes To Maximize Yield & Protect Soil Health.” Youtube, MIGardener, 25 June 2019, www.youtube.com/watch?v=sAFJZ6vkA_4

SanSone, Arricca. “Plants You Should Always Grow Side-by-Side.” Country Living, Country Living, 20 Sept. 2020, www.countryliving.com/gardening/news/g4188/companion-planting/. 

“The Old Farmer’s Almanac.” Old Farmer’s Almanac, Yankee Publishing Inc, www.almanac.com/. 

Vandermeer, John. The Ecology of Intercropping. Cambridge University Press, 1989. 

 

 

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