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  • Boost Harvests with Companion Planting: Top Garden Pairings

    May 10, 2024 10 min read 0 Comments

    A gothic greenhouse with the door slightly open and raised bed gardens filled with muched plantings of lettuce, flowers, herbs planted as companions.

    How to Start Companion Planting

    There are no hard and fast rules to companion planting. What you plant together and how close you plant them will depend on your garden or farm space constraints, the main pests you want to deter, and your ultimate goals. Google “companion planting charts,” and the results will likely overwhelm you. Recommendations are meant to be a general guide on how to get started and how to gauge the results. 

    The Basics of Companion Planting

    Companion planting is a popular gardening and farming method of combining crops that get along well and whose existence may improve the other’s growth and flavor and offer symbiotic benefits. It’s believed to have stemmed from “The Three Sisters” intercropping of corn, beans, and squash perfected by Indigenous people in the Americas over thousands of years. 

    Planting these three crops together brilliantly utilizes the space; they nourish each other by providing nitrogen, support, shade, and protection while suppressing weeds and retaining healthy moisture levels. While growing together, they increase yields and quality while sharing the same space. These crops serve as mainstays in a well-balanced Native American diet. 

    If you want to learn more about the fascinating history and current practices surrounding three sisters planting, this resource from the USDA is well-researched

    When choosing companion plants, select crops with similar soil, fertilizer, and sunlight requirements to plant together and ensure spacing can withstand the mature size of each one. Work with nature instead of against it to yield the best results. 

    a Raised bed with dahilas, lettuce and cherry tomatoes companion planted for more production in a gothic greenhouse.

    Choosing the Right Plant Pairings for Your Garden

    Extensive research has been done to prove that companion planting is effective. Before you throw crops together, do your research because planting certain crops together may have adverse results or attract pests. For example, as mentioned in this Companion Planting Guide from the Franklin Park Conservatory, beans and alliums should be kept well apart. When planted together, these two will decrease each other’s production. You may plant certain plants nearby for aesthetics alone, and that’s ok! As long as the two aren’t poor companions.

    Don’t be afraid to experiment because sometimes companion plants are accidentally discovered. Not all suggested pairings may work in your setup or growing region, so trying what will work for you is best. Keep track of spacing, varieties, and results to reference in future years. 

    Healthy spinach and greens planted with leeks in a raised bed garden.

    Maximizing Yield and Quality

    Finding suitable companions will increase productivity and may improve flavor and nutritional value. 

    Good Companions for High Productivity

    In the early season, when space is limited due to weather constraints, plant green onions and herbs with head lettuce or greens to take advantage of the space between new transplants. The herbs won’t take much from the soil, and their strong scents may help deter pests and hungry critters. 

    Plant a beneficial habitat, or refugia as they’re sometimes called, to attract beneficial insects to your garden or farm. Tunnel growers should take note of this trend, especially if insect netting is used to exclude pests from cash crops growing inside until pollination is needed. Interplant herbs like basil, parsley, cilantro, and chives or flowers like cosmos, marigolds, and borage alongside tomatoes to attract pollinators like native bees, butterflies, and hummingbirds quickly once it is time to remove the netting. Below are just a few benefits of planting each. 

    Basil

    • Can deter thrips, whiteflies, flies, and mosquitoes
    • Benefits from the shade tomato leaves offer
    • Shade helps retain moisture that basil appreciates 

    Parsley

    • Attracts ladybugs
    • May boost tomato growth 

    Cilantro (left to flower)

    • Flowers attract parasitic wasps and hoverflies which lay their eggs on tomato hornworms
    • The scent may deter pests

    Chives

    • Scent repels critters like rabbits, aphids, and mites. 

    Cosmos

    • Cut flower
    • Attract hoverflies that eat aphids 
    • Attract pollinators 

    Marigolds 

    • Repel root-knot nematodes
    • Deters slugs and snails

    Borage

    • Attracts all the pollinators
    • Repels tomato hornworms 

    Related: BENEFICIAL INSECTS FOR GARDENS, FARMS AND GREENHOUSES


    Another lesser-discussed benefit of companion planting is using them as an indicator of disease that may be on the horizon. Crops like basil will contract powdery mildew before tomatoes. Joe Masabni, Ph.D., a Texas A&M AgriLife Extension Service vegetable specialist, indicates in this article that you may preemptively treat your tomatoes before they contract the disease after noticing it on the basil. 

    This may go without saying, but yields, plant growth, and health will improve if pest pressure decreases and pollination increases. Healthy plants are more abundant, which translates into more revenue. 

    If you’re ready to take your tomato production to the next level, plant some known tomato companions and note the results. Just remember that the timing of each planting is important to reap maximum benefits. 

    Onions and ranunculus interplanted in a raised bed.

    Improving Taste and Nutritional Value

    Scientific studies are yet to explicitly prove that growing specific crops side-by-side improves the flavor and nutritional value. However, an analysis of the allelopathic properties provided by basil when grown with tomatoes showed that companionship was an effective alternative to fertilizing the tomatoes. The Chesapeake Bay Governor’s School student study results showed that germination rates, root mass, and yields of the tomatoes increased

    Many gardeners swear planting basil near tomatoes increases the sweetness profile. Since they make good neighbors and have similar growing requirements, give it a shot and find out for yourself. 

    Red romain and lettuce interplanted with herbs in raised beds in a greenhouse.

    Eco-Friendly Pest and Weed Management

    Many natural pest and weed control strategies exist in plants. Strategically place certain herbs, plants, and flowers to control these issues without chemical inputs. Less time cultivating leaves more time for other tasks, increasing the value of the crops. Time is money! 

    Natural Pest Deterrents Through Strategic Pairings

    Integrated pest management (IPM) is one of the coolest benefits of companion planting, and you can do it effortlessly after some experience and a little trial and error. In essence, IPM with companion planting is defined as paying attention to the plant companions Mother Nature has provided us and taking advantage of them instead of working against her. 

    Trap cropping is a tried and true method that uses companion planting to actually attract pests to your plot. 

    You may be wondering why you would do this. Here are a few studies that show positive results: 


    • A New England Vegetable & Berry Growers’ Association study showed great success when using ‘Blue Hubbard’ squash to attract cucumber beetles and squash vine borers. Transplant them about two weeks before your squash and zucchini so it’s larger than your cash crop.
      When planted at the corners or entirely surrounding a patch of summer squash and zucchini, the pests will almost always choose ‘Blue Hubbard’ as their meal, in this case, 88-95%, leaving the cash crop unsprayed and safe from damage. Spraying the trap crop is an effective method to trap and kill the pests. If you choose not to spray, you must scout for and kill the pests by hand found on the Blue Hubbard plants to keep them from reproducing and moving onto your cash crops. Otherwise, it will succumb to pest pressure, and you will not experience the benefits.
    • The strong scent of marigolds has been shown to deter the hawk moth that lays hornworm eggs. Establish marigolds early and place them near your tomatoes and peppers, which large populations of hornworms can destroy overnight.
    • Attract beneficial insects like ladybugs and green lacewings to eat hornworm eggs. Predatory wasps like the brachonid and Trichogammid will lay eggs on large caterpillars. When the eggs hatch, the larvae will feed on the bodies of the hornworm, so if you see a parasitized hornworm, leave it in place! 
    • Grow French marigolds as a cover crop and work the debris into the soil once the crop is terminated. The biochemicals produced by the flower are toxic to root nematodes and are released into the soil when worked in. 
    • Nasturtiums are another strongly-scented annual flower that attracts aphids and squash bugs, along with beneficial hoverflies who happen to prey on aphids. Plant these near brassicas for protection. 
    • Flea beetles are small, but their damage can be devastating, especially for young brassica transplants like collards and kale—plant radishes, Chinese cabbage, or pak choi nearby, which they tend to prefer. Alternatively, confuse pests by planting multiple highly-fragranced herbs like lavender and catnip. Confirm any local catnip regulations before planting it in the ground, as it’s considered invasive in some areas. 

    Identify a crop that pests in your area love to munch on more than your cash crops and plant it strategically nearby to deter them. Experiment with placement and perimeter trap cropping (PTC) by fully surrounding your main crop so pests are encouraged to go after the trap crop. 

    boy choy planted in a raised mulched bed with onion scapes companion planted nearby.

    Using Plants as Organic Weed Suppressants

    Shallow-rooted crops like blueberries must receive plenty of water so they don’t dry out. And since there is a large amount of bare soil around them until they leaf out for the season, growing a trusty companion will help retain moisture and suppress weeds as they establish. This is especially beneficial for newly transplanted bare-root plants. 

    Thyme, sage, and chives are easy-to-grow herbs that play nicely with blueberries. They may repel pests like the Japanese beetle and aphids while increasing moisture retention and weed control while attracting pollinators. An unlikely and beautiful pair that may work is strawberries in the space around blueberries. They won’t compete for nutrients and may have a similar harvest window. 

    Sweet alyssum is a fantastic option that serves as a pest deterrent, beneficial insect attractant, and weed suppressant. It forms a soft carpet around nearby plants and emits a sweet, floral fragrance. Its tiny flowers are perfect for tiny pollinators. 

    Enhancing Soil Health and Structure

    Providing your soil with root system diversity can positively impact overall soil health, drainage, and nutrient uptake. Think of it like working all the muscle groups of your arm instead of only focusing on the biceps. This principle applies to crop rotation and diverse roots growing together simultaneously. 

    Complementary Roots for Soil Improvement

    Interplanting annuals with perennials is a great example of blending root systems. Perennials typically have extensive root systems that run deep, which are required to hold them steady and help them stay healthy throughout the seasons and withstand inclement weather patterns. We know the soil greatly benefits when living roots are constantly in the ground, and combining annuals with perennials makes this easy to maintain. 

    Different types of roots attract different types of microbes. Having a variety of these guys working for you in your soil will build healthier plants that can ward off pests and diseases, retain moisture while avoiding erosion, and support the soil food web. 

    Diverse root systems help provide proper infiltration and assist with nutrient uptake. Longer roots can help break up compaction and reach deep nutrients, while shallow roots can help maintain topsoil levels and avoid erosion. Additionally, when plant debris of legumes like cowpeas and beans breaks down in the soil, nitrogen is fixed and made available to the next round of crops. Planting brassicas or potatoes after a legume cover crop begins to break down allows them to take advantage of nitrogen-rich soil. So, while this isn’t a simultaneous companion plant, the soil benefits the legumes offer directly affect the success of the following crop.  

    Efficiently filling garden space with diverse root systems reduces overcrowding while utilizing all the available space. This cuts down on time weeding and keeps the soil moist and shaded. 

    Raised beds with a mulched pathway in a gothic greenhouse showing a variety of interplanted flowers, brassicas, and spinach companion planted with irrigation.

    Plant Interactions that Boost Nutrient Uptake

    The extreme alternative to companion planting is monoculture, which we know causes shortages of soil nutrients and microorganism diversity, eventually decreasing soil fertility. As the soil is stripped of its value, that crop eventually becomes harder and harder to grow successfully. The result is barren, unproductive land. 

    Proven companion plants complement their neighbor's growth instead of inhibiting or competing for water and nutrients. This symbiotic relationship leads to increased access to nutrients for all. 

    The Economic Benefits of Companion Planting

    So far, all the benefits we’ve discussed impact your crops' overall health, which should translate into higher revenue. Now, let’s talk about the effect on the economics of companion planting. 

    Reducing Costs with Fewer Chemical Inputs

    The more we use organic pest control sprays, the more resistance to treatment pests are thought to develop, deeming them less effective in the same amounts each season. Farmers must, in turn, purchase more products, creating an endless cycle of pest control and damage and increased funds spent on controlling pests. 

    Strategically place host plants for beneficial insects near cash crops its prey is known to damage. Think of their presence as free and willing labor in the garden. They’re attracted to your garden for access to free housing, food, a place to raise their brood, and protection. In return, they take care of garden pests. Everybody wins. 

    The US Environmental Protection Agency (EPA) is responsible for testing, regulating, and monitoring ingredients of farm inputs and their effects on humans, wildlife, water, and soil. Conventional pesticides are produced synthetically, while naturally occurring pesticides are derived from things found in nature. While these might seem like good alternatives to conventional pesticide options, remember that everything you put on your crops and into the soil has a lasting effect, including negative impacts on native insects, birds, and pollinators. 

    Studies show by limiting our exposure to certain chemicals and carcinogens, we lower our risk of developing health issues like cancer, hormonal disruptions, inflammatory diseases, and congenital disabilities. Fewer chemicals in our food and soil lower our risk of developing these. 

    Celery planted in raised beds in a greenhouse.

    Increasing Market Value through Companion Strategies

    I briefly mentioned interplanting green onions with newly transplanted head lettuce to utilize valuable, early-season bed space. Think outside the box and imagine growing celery down the middle of your Swiss chard, dill alongside your trellised cucumbers, and 

    Pay attention to days to maturity, sun and water requirements, pH levels recommended, and other growing needs. Plant crops with similar needs together that won’t compete for the same nutrients and whose proximity will benefit the other. You’ll have more to offer at the market, increasing the value of your space. 

    FAQs

    What Are Some Classic Companion Plant Pairings?

    Many companion plant duos are simple to remember. Think about items you often pair in the pan and on your plate. Those usually grow well together, too! 

    1. Basil and tomatoes 
    2. Brassicas and onions 
    3. Cucumbers and radish
    4. Marigolds and peppers
    5. Peas and dill
    6. Summer squash and radishes 
    7. Nasturtium and broccoli 
    Marigolds densely planted as a companion plant in the garden

    Can Companion Planting Really Increase Profits?

    By companion planting a short-term crop with a long-season crop, profits from the companion are a bonus. Calculate the profitability of your farm by dividing the total profit by the total bed space used for a specific crop. The result is how much that crop brought in per square foot. However, when you add the revenue the companion plant brought in (not to mention the non-monetary benefits you observed), that bed space increases its value to your farm. 

    A perfect example is adding a quick, shallow-rooted crop like radishes, beets, or green onions alongside our newly transplanted tomatoes. They don’t take much from the soil, and we get an entire second crop from the same bed space, allowing us to increase profits from each of those garden beds. We grow tomatoes in a high tunnel, the most valuable space on the farm. Tomatoes are in the ground all season, so growing additional crops on the outside edges of those beds increases our profits substantially. 

    Lettuce mix alone is planted in a 100 ft garden bed, and the first harvest yields 100 pounds. It is sold for $6/lb, equalling $600 or $6/ft. Now, let’s say you interplanted green onions alongside the lettuce mix, and in the same period, you harvested 100 bunches that you sold for $3.50 each, adding $350. As a result, each foot of bed space now brings in $9.50 of revenue, totaling $950/bed. Based on this simple example, I’ll let you decide if companion planting can really increase profits. 


    Written by Jenna Rich of Partners’ Gardens LLC