Companion Planting: The Real Benefits

 

Companion planting of Brassicas and onions

With the holiday season over and winter settled in, perhaps planning your garden will warm up some of those dreary winter days.  There are lots of things to consider when planning out the vegetable garden. If you haven't yet considered companion planting make this the year you do.

  Companion planting is the practice of interplanting or intercropping two or more plants to achieve some benefit. While info on beneficial companion plants has been passed around among gardeners for generations not all the info is based on verifiable results a lot is folklore.  There is, however, a renewed interest in research on companion planting. New trendier terms may be used in place of companion planting such as polycultures, intercropping, and interplanting, but the beneficial results are the same. New studies are focusing on how companion planting is a way to create a ecosystems of organisms and food webs that are mutually beneficial to each other.  While that may sound complicated it's not.

Intercropping of sweet corn and pumpkins and winter squash.

Lets clarify some terms before diving into the benefits of companion planting.

In studies and research you probably won't hear the term companion planting but you will find others terms referring to the same concept.

Polyculture:  a system where multiple plants are are planted to mimic the biodiversity of nature.  This creates less disease and pest pressure than a mono culture.

Intercropping:  Planting multiple crops in the same field to yield some benefit.

Interplanting:  a smaller scale version of intercropping and mixing multiple plants in the same space.

Monoculture:  for clarification a monoculture would be one field, raised bed, or row of the same crop.

All terms mean the same thing:  increasing the diversity of plants to achieve a benefit.  I personally seem to use the term interplanting or companion planting because it seems a better fit for the home gardener.

Companion planting of brassicas, onions, and celery.

Benefit 1:  Pest Management

Pest management is probably the most well know benefit.  How does it work?  Pests find  and recognize their target plant using the volatile chemicals emitted by the plant. The correct companion plant can mask or hide these chemicals. Avoiding a monoculture makes it more difficult for a pest to find its host plant.  While not completely eliminating a pest it does reduce pest loads.

When this is your purpose remember not all claims on the internet are backed by research.  Here are a few that are researched and are companion plantings I utilize in my garden.

Peppers & Onions  

• Deter green peach aphids  
• Onions mask volatile chemicals from peppers from aphids

Zucchini & Nasturtiums

• Deter squash bugs 
• Reduced numbers by masking volatile chemicals

Cole Crops & Dill

• Deter imported cabbage worm
• Reduces egg laying by adult cabbage worms which are butterflies

Onions, cabbage & marigolds

• Onion and cabbage root maggots
• Marigolds mask volitive chemicals making it hard for the adult flies to find their host plant.

Benefit 2:  Encourages Beneficial Insects in your Garden

Biological control is when one living organism is used to control the population of another.  Beneficial insects provide pest control in two ways: predators directly eat their pests while parasitoids lay eggs inside a pest and the developing young consume the pest from the inside out.  It's like something out of a horror movie, right?  

Beneficial insects need 3 things to thrive in your garden:

1. A pesticide free environment

2.  Carbohydrate rich nectar which is the food of the adult insect

3.  Prey insects for the larvae of the beneficial insect.

Companion plants invite beneficial insects into your garden and encourage them to stay. 

Sweet Alyssum & Lettuce

• The nectar is attractive to the syrphid flies and parasitic wasps whose larvae feed on aphids

Flowering Herbs in Carrot Family such as carrots, dill, fennel

• Attractive to parasitic wasps which lay their eggs on caterpillars
• Lacewings lay their eggs on the dill in my garden and larvae devour aphids

Flowers in the daisy family and Cole crops

• The daisy family attracts ladybugs, lacewings, and parasitic wasps.

The world of beneficial insects is fascinated and I will soon be doing a separate post on these creatures.  For now just plan on creating and implementing practices that will help them thrive in your garden.

Additional Benefits

There are additional benefits and reasons to intercrop or companion plant including weed suppression and building soil.  Also it looks beautiful to mix your plantings with herbs and flowers.  I focused on groupings that I have tried and that I know have worked. I wouldn't devote too much energy to overthinking this just keep in mind the goal is to create more diversity within each garden bed which benefits plants and the soil biology.

 

Dill which attracts beneficial insects.