Companion planting: who likes eachother?

by Wally Richards

Planting time is an opportunity to look at which plants benefit from being beside eachother and which do not.

To start with, let’s look at our gardening friends that live in the soil, microbes (bacteria) and fungi. There is a ratio that forms in soils where one group of these will be more dominate than the other, while both will provide vast benefits to your plants.

We find in natural forests that the fungi are kings, where on natural grasslands the microbes rule. Thus our trees and shrubs (small trees) prefer lots of fungi to do best. Our lawns, vegetables and flowers want their mates the microbes.

There are exceptions to this rule as nature is not finite in its preferences, such as strawberries which live and perform best in soils with ample beneficial fungi and fewer microbes.

We notice that grass and a number of other plants do not do well near trees and shrubs.

Certainly it can be the aspect of shade and the trees taking out moisture and nutrients from the soil. When we apply ample moisture and nutrients, as well as removing the lower branches to afford reasonable natural light to these plants and grasses, they still do not do as well as the same plants a bit further away. The added moisture and food certainly makes the trees grow bigger and faster.

It is to do with the balance of the soil life. I love trees for the shelter and shade they provide but have always found my vegetables growing near the trees are never as good as the same ones a bit further away.

There is a certain amount of proven science about some companion planting and the rest is unproven. Much has been noticed by gardeners over hundreds of years and this is termed traditional knowledge.

One of my favourites is the planting of corn seeds and once these plants are up a foot or so then bean seeds (or peas) are planted next to each corn plant. Later when the beans have started to climb up the corn, squash seeds are planted in amongst them. This is a traditional planting by the North American natives in some tribes. One can see the immediate benefit of the beans or peas having the taller corn plants to climb up or support and the larger leaves of the squash aiding in the retention of soil moisture.

But beans and peas are nitrogen fixers and corn and squash need heaps of natural nitrogen to grow well. This same planting can be applied to tall growing sunflowers too.  We have in these two cases very beneficial companion plantings.

Clover is also a great nitrogen fixer. Here is an interesting case I was told about in regards to clover and Roundup.

The group of farmers who use the mineral rock dust they call ‘Probitas’ did a trial in two paddocks next to each other. One paddock was sprayed with Roundup to kill the grasses and weeds then ploughed. The other paddock was just ploughed with no herbicide used. Probitas (Mineral Rock dust) and lime were applied to both paddocks and then tilled. Then clover seeds were drilled planted in both. The clovers grew in both paddocks but the non Roundup treated paddock had better looking plants. Later some clover plants were lifted in both paddocks to check the root nodules which fix the nitrogen. In the Roundup treated paddock the nodules were small and sparse. Where in the non Roundup treated paddock the root nodules were large and like bunches of grapes. A very interesting result which shows how much harm is done to the soil with these types of herbicides.

Now let’s look at a few examples of common vegetables and what can be planted next to them and what should not.

  • Asparagus likes tomatoes, parley and basil
  • Climbing beans like corn and radish but not onion, beets kohlrabi and sunflowers
  • Dwarf or bush beans don’t like onions but like potatoes, cucumber, corn, strawberry, celery and summer savoury
  • Brassicas (cabbages etc) like aromatic herbs, celery, beets, onion family, chamomile and chard but not dill, strawberries, climbing beans and tomatoes
  • Carrots like peas, lettuce, rosemary, onion family, sage and tomatoes but not dill
  • Celery is happy with onion & cabbage families, tomato, dwarf beans and nasturtium
  • Corn likes beans, pea, pumpkin, cucumber and squash but not tomatoes
  • Cucumbers like beans, corn, peas, sunflowers and radish but not potatoes or aromatic herbs
  • Eggplant likes beans and marigolds. Lettuce prefers carrot, radish, strawberries and cucumber
  • Onions do well with beets, carrots, lettuce, cabbage and summer savory but not beans or peas
  • Parsley prefers tomatoes and asparagus
  • Peas like carrots, radish, turnip, cucumber, corn and beans but not onion family, gladiolus or potatoes
  • Grow your spuds along side of beans, corn, cabbage family, marigolds and horseradish avoiding pumpkin, squash, tomato, cucumber and sunflowers
  • Pumpkins get on well with corn and marigolds but not potatoes
  • Radish like peas, nasturtium, lettuce and cucumbers but avoid hyssop
  • Tomatoes prefer onions, nasturtium, marigolds, asparagus, carrot, parsley and cucumber but not potatoes, fennel and cabbage family
  • Turnips like peas but not potatoes

Likely there are many others but this is a good starting point for those that wish to use the system of companion planting.

Another reason for planting different plants together is insect pest control.

The African marigold releases thiopene which is a nematode repellent, making it a good companion for a number of garden crops. There are plants that attract beneficial insects because they provide a nectar source for them. Phacelia Lacy has proved popular with some for this purpose attracting bees and predictor small wasps (the wasps kill the aphids by laying their eggs in the aphid’s body).

Another way is to plant a Shoo fly plant which attracts white fly and helps keep the pest off your other plants. I don’t know how well this works in reality but the Shoo fly plant certainly gets covered in whitefly.

I remember once that I converted some waste land for a crop of potatoes and found that mint was growing in the area. I left the mint to grow hoping that I would not need to mint the potatoes when boiling. It didn’t work the potatoes never gathered the mint flavour.

Another interesting aspect is gardening by the moon phases. For instance it is said that you should plant seeds when the moon is ascending and harvest when descending. I understand that when the moon is up and especially around full moon time on a clear night that the sun light reflected off the moon gives plants some light which allows them to grow when compared to a no moon time.

When I was a nurseryman I was planting seeds virtually everyday and never noted a better response to ascending or descending moon. I also asked other nurserymen the same and they also said it appeared to make no significant difference. (Moonlight or artificial light at night will make sprouted seeds grow bigger quicker). So is there any truth in gardening by the moon to obtain better results?
I believe so because of our own conscious thoughts. If we believe something is going to grow better because of an X factor and hold that thought in mind while gardening the plants  will respond.

It is like growing two identical plants in pots near each other. You tell one how much you love it and the other you say how bad it is. Do this daily and the bad one will fair poorly and likely die where the good one will grow lush and happy.

Now if we could only apply this to our weeds it would solve a  real problem.

2 comments on “Companion planting: who likes eachother?

  1. Michael Schoombie on said:

    How do i get rid of oxsailis from my vege patch?I have been told chickens will eat the bulbs but I suspect the bulb will pass through the chicken and be fertilized before fallinng to the ground.
    Steam sterilisation would be an option but to expensive.
    Using a garden sieve great for the big bulbs but the little blighters

  2. Hi Michael, yes that is one of the ways and I have tried it myself… it was not very successful as the chickens don’t eat every last scrap and tend to disperse the bulbs. Here are some tips from Wally Ricahrds – regards


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