Vegetable Friends and Families (and enemies?)

There is plenty of online chatter about "companion planting" and "trap cropping" in the vegetable garden.  But what does that mean?

Basically:  some plants are (possibly) helpful to other plants.

Beans (and also marigolds) at Haiku Farm

Digging a little deeper:

A common companion-planting scheme is the Three Sisters Garden, in which the three crops of squash, beans, and corn are interplanted on the same plot of ground.  

The theory is that bean plants enrich the soil to feed the corn and squash.  Squash plants sprawl over the ground, shade the soil and choke out weeds around beans and corn.  Corn plants grow tall and provide a trellis for beans to climb.

Typical Three Sisters planting plan

This is often touted as a "Native American practice" without citing which of the 1000+ tribes, bands and family groups scattered over 3.8 million square miles use(d) the method--a bright flashing light to alert us that important details are being overlooked.

The reality of Three Sisters planting is that these can be good companions with different yet compatible needs for light, space, water, and soil nutrients.  

However, the results on fertile, well-irrigated sandy-loam soil will be very different from results in arid regions or on clay soil.  Some gardeners report higher yields from all three crops--but more report that one crop may benefits from their partners where the others are hindered.

Some types of companion plantings are supported by research.  

• Garlic, onions and other alliums are known to repel deer and caterpillars
• Rosemary discourages cabbage loopers, carrot flies and bean beetles
• Dill attracts bees and other pollinators
• Nasturtiums attract aphids that will otherwise feed on food crops
• Marigolds attract beneficial pollinators and also trap snails and other pests

Not all plants are friendly to other plants.  As one of our bean growers has noticed, the beans he planted near some onions do not seem to be growing enthusiastically.  

WSU research points to many good companions for onions, but "beans" aren't on the list.

Mark's onions are growing well, but the beans lack "oomph"

At Haiku Farm, we have volunteer calendula, marigolds, nasturtiums, dill and sunflowers scattered through our veg patches.  We allow them to grow where the birds have planted them, except when they are clearly interfering with other crops. 

• The calendula and marigolds are companion plants, repelling pests from our beans.  
• The nasturtiums are trap plants, luring pests to themselves and away from the beans.  We clip off the bug-damaged nasturtium leaves or uproot the the whole plant and dispose of it.
• The dill and sunflowers are pollinator attractors, luring beneficial bugs to the garden.

Sunflowers are shading the bean plants, and will probably have to be removed. 
The dill and marigolds can remain in place.

Some people would say this makes our gardens more chaotic--we prefer to think of them as pretty.

Companion planting and trap cropping research links:

Gardening with Companion Plants https://pubs.extension.wsu.edu/product/gardening-with-companion-plants-home-garden-series/ 

Trap Cropping  https://s3.wp.wsu.edu/uploads/sites/2073/2020/07/Trap-Cropping.pdf

Planting Chart for Companions https://s3.wp.wsu.edu/uploads/sites/2056/2018/10/Cool-Season-Planting-Chart-for-Companion.pdf

Three Sisters Project  https://threesistersproject.language.iastate.edu/research-results/