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The Comprehensive Guide to Companion Planting

January 11, 2024

Using a garden planting strategy to help grow, protect and maintain your plants

Introduction

Gardening, a timeless activity, offers endless opportunities for learning and experimentation. One of the most fascinating aspects of gardening is “Companion Planting,” a practice that can significantly enhance the health and yield of your plants. This guide delves into the heart of companion planting, exploring its definition, biological mechanisms, and practical applications for both vegetables and flowers.

What is Companion Planting?

Companion planting is an agricultural practice that involves growing different plants in proximity for mutual benefit. This method has been recognized and used for centuries by various cultures around the world. It relies on the natural relationships between plants to create a healthier, more productive garden or farm. Here’s what companion planting provides

  • Pest Prevention – Certain plants can deter specific pests naturally. For example,
    • Marigolds release a substance from their roots that repels nematodes.
    • Garlic and onions can deter rabbits and deer with their strong scent.
    • Herbs like mint and basil can help keep away various insects.
  • Natural Shade – Larger plants can provide shade for smaller, more shade-tolerant plants. This natural shading can protect delicate leaves from the harsh sun, reduce water evaporation, and cool the soil, creating a microclimate that benefits certain plants.
  • Improved Nutrient Utilization – Some plants, like beans and other legumes, fix nitrogen in the soil, which benefits neighboring plants that require more nitrogen to grow.
  • Spatial Interactions – Companion planting maximizes space usage by combining plants with different growth habits or rates, like tall sunflowers with low-growing strawberries.
  • Attract Beneficial Insects – Flowering companions can attract pollinators necessary for fruit and vegetable plants to produce crops. They can also attract beneficial insects that prey on pest species.
  • Soil Health – Deep-rooted plants can help to break up the soil, which can aid in the growth of plants with shallower roots. Additionally, some plants can help to suppress weeds, thus maintaining soil integrity.
  • Plant Support – Tall, sturdy plants can serve as natural trellises for climbing plants like peas and beans.
  • Disease Suppression – The diversity of plants in companion planting can help prevent the spread of plant diseases that might otherwise wipe out a monoculture.
  • Increased Biodiversity – Companion planting encourages a diverse ecosystem which can lead to healthier soil and plants, and can also support a wider range of wildlife.

In essence, companion planting is a holistic approach to gardening and farming that considers the complex interplay between different plant species and leverages these relationships to create a more dynamic and resilient growing environment.

Historical Background

Rooted in ancient agriculture, companion planting has been practiced worldwide for centuries. Indigenous peoples have long understood its benefits:

  • The Native Americans used the “Three Sisters” method (corn, beans, and squash), where each plant supports the others.
  • In Asia, particularly in China and Japan, farmers practiced intercropping with rice and fish, creating a balanced ecosystem.
  • Ancient Egyptians planted wheat and barley together, which improved soil fertility and yields.

These historical practices laid the foundation for modern companion planting principles.

The Biology of How It Works

Companion planting works through several biological mechanisms:

  1. Nutrient Sharing – Different plants require varying nutrients from the soil. When compatible plants are grown together, they can optimize the use of soil nutrients.
  2. Pest Control – Certain plants can repel pests naturally, protecting neighboring plants. For example, marigolds emit a substance that deters nematodes and other pests.
  3. Pollination Support – Planting flowering companions can attract pollinators, which is beneficial for fruit and vegetable plants needing pollination.
  4. Physical Support – Tall plants can provide shade or support for smaller plants. For instance, corn stalks can serve as natural trellises for climbing beans.
  5. Allelopathy – Some plants release chemicals that can inhibit or promote the growth of other plants. This phenomenon is known as allelopathy.

Vegetable Common Companions

In vegetable gardens, companion planting can boost yields and reduce pest issues:

companion plants for tomatoes
Companion for tomatoes? Basil, not only in your cooking but in the garden.
  1. Tomatoes – Basil enhances flavor and repels flies and mosquitoes. Marigolds deter nematodes.
  2. Carrots – Planting carrots with onions can help repel carrot flies.
  3. Lettuce – Growing lettuce under taller plants like tomatoes or beans provides necessary shade.
  4. Peppers – Companion plants for peppers include onions, spinach, and tomatoes.
  5. Beans – Corn and beans work well together, as beans fix nitrogen in the soil which benefits corn.
companion plants for onion
The best companion for onions are carrots.

Flower Common Companions

Flowers not only add beauty to the garden but also support companion planting:

  1. Marigolds – Great companions for many vegetables, repelling pests and attracting beneficial insects.
  2. Nasturtiums – Ideal for planting near squash and cucumbers to repel pests.
  3. Sunflowers – Attract pollinators and can provide shade or support for smaller plants.
  4. Lavender – Known for its aroma, repels deer and rabbits, and attracts pollinators.
marigolds as a companion plant
Marigolds, or Calendula, are great companions for tomatoes, onions, carrots and just about anything else you grow.

Additional Companion Planting Tips

  1. Herbs – Many herbs like rosemary, thyme, and mint are excellent companions due to their strong scents that deter pests.
  2. Avoiding Bad Combinations – Just as some plants benefit each other, others can be detrimental. For example, garlic and onions can inhibit the growth of beans and peas.
  3. Crop Rotation – Rotating crops in subsequent years can prevent soil depletion and pest buildup.
  4. Soil Health – Maintaining healthy soil is crucial for successful companion planting. Regular composting and mulching can significantly improve soil quality.

Full Companion Planting Chart

Below is a plant companion chart of the most common pairings/companions for a healthy garden.

PlantCompanions
AsparagusTomatoes, Parsley, Basil
BeansCorn, Squash, Marigolds
BeetsOnions, Cabbage, Marigolds
BroccoliCelery, Chamomile, Rosemary
CornBeans, Squash, Peas
CucumberBeans, Celery, Dill
GarlicBeets, Kale, Potatoes
KaleBeets, Celery, Cucumber
LettuceCarrots, Radish, Strawberries
OkraPeppers, Melons, Cucumbers
OnionsBeets, Carrots, Lettuce
PeasCarrots, Cucumbers, Corn
PeppersBasil, Onions, Spinach
PotatoesCorn, Cabbage, Marigolds
RosesGarlic, Onions, Marigolds
SquashBeans, Corn, Nasturtiums
StrawberriesSpinach, Lettuce, Borage
TomatoesBasil, Marigolds, Asparagus
A companion planting chart for the garden

This table can serve as a reference for planning your garden and implementing companion planting strategies.

The Anti-Companion Chart

As in life, there are things you should do, and things you should not do. Here is the “anti-companion” plating list for your garden, or pairings you should avoid.

Vegetable 1Vegetable 2Reason for IncompatibilityAdditional Considerations
TomatoesPotatoesIncreased risk of blight and other diseases
BeansOnionsOnions can inhibit the growth of beans
CarrotsParsnipsAttract similar pests, increasing infestation risk
CucumbersAromatic herbsSome herbs can inhibit growth, others are beneficialDill and borage are exceptions, attracting helpful insects
BroccoliStrawberriesBroccoli can hinder strawberry growth
PeasGarlicGarlic can inhibit the growth of peasSimilar to onions, the effect is somewhat debatable
CabbageCauliflowerCompete for the same nutrients, attract same pests
AsparagusGarlicGarlic can stunt asparagus growth
LettuceCeleryDifferent water needsCelery requires more water than lettuce
SpinachPotatoesPotatoes might inhibit spinach growthThe evidence is mixed
RadishesHyssopPotential growth stunt, but limited information
BeetsPole BeansPole beans can inhibit beet growth
ZucchiniPumpkinsRisk of cross-pollination affecting seed qualityNot an issue unless saving seeds
OnionsPeasOnions may inhibit pea growthThe allelopathic effect is debatable
CornTomatoesPotential for increased pest environmentNot specific pest attraction, but general risk increase
Incompatible planting table, or Companions to avoid

Conclusion

Companion planting is a sustainable and efficient way to enhance your garden’s productivity and health. By understanding the relationships between different plants and utilizing their natural synergies, gardeners can create thriving, diverse, and ecologically sound gardens. Whether you’re a seasoned gardener or a beginner, incorporating companion planting into your garden strategy can yield fruitful and rewarding results. By embracing these practices, you not only grow plants; you cultivate harmony and balance in your garden ecosystem. Companion planting is indeed a testament to the interconnectedness of nature and the wisdom embedded within it. Happy gardening! If you have other questions, you can read our companion planting guide.

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