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Companion Planting

Companion Planting a beginners Guide.

When it comes to arranging our vegetable gardens we have a tendency to lump all plants of the same type together in beds, a practice known as monoculture. Gardening just seems easier when things are organized like that, but it may not actually be the best way forward.

Monoculture methods have been popular since the industrialization of agriculture but in nature we seldom see monocultures. Wild plants thrive in diverse ecosystems because they have evolved over millions of years to embrace natural synergies, so there has been some debate over whether monocultures are actually beneficial in the long run.

Companion Planting

The alternative is polyculture, where we plant several crops together in the same space, or at least, near one another. We call this companion planting when one plant actively helps another. Certain plants are extremely beneficial to others, while some can be harmful. So we need to choose the members of our plant communities carefully.

By creating polycultures we not only end up with a healthier garden but perhaps a more beautiful one, where different kinds of leaves and flowers burst together with colour and life to fill in the gaps created in monocultures.

Why Companion Plant?

Companion planting is undertaken primarily to increase yields, control pests and aid pollination.


Intercropping is the practice of planting two or more plants together on the same piece of land in order to maximizing growing space and increase yields.

The simplest example of intercropping is growing a short crop that does not require much light in between rows of a tall crop. For instance, you might try planting leeks between cabbages, or onions between lettuces.


Another simple kind of intercropping involves sowing fast growing crops between rows of slower growing crops. The idea here is to harvest the quicker growing crops before the slower growing crops get bigger and steal their light. An example of this kind of intercropping would be planting spring onions between tomatoes, or radishes between cabbages.

We might also practice intercropping according to nutrient needs. For example, we could put a crop that needs a lot of nitrogen, like cabbages, together with a crop that creates nitrogen, like peas, to reap the benefits of natural fertilization.

You might also do combinations of intercropping methods. Perhaps the most famous example of this is the Aztec’s maize growing method. You might want to replicate it, since it is a good place to start with intercropping. They would plant sweetcorn, squashes (or courgettes) and runner beans in the same plot. As the corn begins growing it provides a readymade support structure for the beans to climb up. In turn, the beans suck nitrogen from the air and fix it in the ground which then feeds the corn and gives a boost to the cobs. The purpose of the low growing squashes it to shade the ground in order to keep it moist and weed free. This method will boost yields and save space by up to fifty percent.  

Disease / Pest control

Companion planting is also an excellent (and organic) way to reduce the amount of diseases and pests that might attack your crops.

By their very nature, monocultures lead to pestilence outbreaks because they provide unnatural environments within which any epidemic can quickly spread. The Irish Potato Famine is a famous example of a plant epidemic made more devastating by the fact that everyone basically just grew the same strain of potato in monocultures.

But polycultures are less susceptible. Imagine a plant is attacked by aphids or root fly. They would have a much harder time spreading through the patch if the adjacent plant was of a different species. Additionally, taking a companion planting approach makes it difficult for pests to locate an area they want to attack in the first place. This is because when different plants are mixed up on a plot, so are the smells which attract pests.

Some plants don’t just confuse, but actively repel pests. So we can use them to shield plants that are vulnerable. The classic example of this is to companion plant carrots and onions. The carrot flies which can devastate a crop cannot abide the smell of onions, so will leave the whole bed well alone.

Baby Carrots

We generally want to grow both carrots and onions for food so they make an excellent match. But sometimes we may need to use plants that are not usually eaten in order to repel insects. For example we might choose to plant nasturtiums near cabbages to repel the cabbage white butterfly.   

We might also use plants that attract beneficial pest-eating animals so that they will devour the attackers for us. Hoverflies and ladybirds are two excellent policemen of garden pests. They both love to feast on juicy aphids and are generally attracted to bright and distinct smelling flowers. Any good flower will do, but fennel is an edible plant that will bring them in. Try growing fennel near cabbages and watch the aphid population naturally decline.

With these methods we can more closely mimic the ecosystems of the natural world and reduce the need for chemical pesticides. It is a good idea to dedicate about 10 per cent of your growing space to beneficials.


We also use a kind of companion planting to attract pollinating insects such as bees into the garden. When bees come to collect nectar from the attractive plants they will also take the time to pollinate your crops. This will improve yields and the vitality of your plot.

Bees are mostly attracted to plants that have huge, bright flowers. So you could try planting different flowers to bring them in, any kind of flower garden favourite will do. Try marigolds or chrysanthemums between crops, and even roses around borders. Snowdrops, pansies, crocuses and hyacinths are also excellent choices, but you wouldn’t normally want to eat any of those.  

Sunflowers are perhaps a better choice for the food gardener because you can eat the seeds. Plus they grow very high with thin stalks, so do not get in the way and block light. Poppies with edible seeds are great too for the same reasons, and both of those flowers also look fantastic.

There are also some herbs that are very attractive to bees. Rosemary has a smell in springtime that is very attractive to pollinators and humans alike. Sage attracts bees during early summertime and chives bring them in towards late summer. So, if you border your garden with these three herbs you will have the whole year covered regarding bees.

If you watch bees closely you will notice that they much prefer to fly in rays of sunshine. This is because they actually need the sun to fly. So if you do plant flowers to attract bees, try planting them in sunny areas, and if you find a downed bee, put it in the sun and soon enough it will take off again.

Companion Plant Combinations

Let’s look at some interesting companion plant combinations for you to try:

Alliums such as garlic and onion are good companions for any crop that is troubled by slugs or flies. Plant them near brassicas, potatoes or carrots.

Asparagus protects tomatoes from the pests that attack them and tomatoes return the favour. The two go well together in the garden and on the plate.

Beans and peas should be planted near anything that requires a lot of nitrogen. Brassicas such as cabbage and cauliflowers are a prime example, however, legumes will also improve the growth of beetroots and potatoes. However, you need to be careful if you have put alliums near any of these crops since they stunt the growth of peas and beans.

Beetroot has no enemies, it will grow well with most plants. However, peas and beans will feed it and garlic will protect it.

Herbs are great companions for any plant troubled by pests. We might love the smell of herbs but many garden creatures do not.

Basil repels mosquitoes so it might make a good companion for humans that have a problem with them.  It also improves the flavours of certain plants such as tomatoes and lettuce.

Chives deter aphids and other fruit pests. They grow well under shady spots, so it might be a good idea to plant them under fruit trees.  

Dill brings insects into the garden which eat aphids but it also helps to improve the growth of cabbages.  

Parsley improves the flavour of both tomatoes and asparagus.  

Sage protects most plants from pests, but should be kept away from cucumber because it is poisonous to that crop.

Thyme is a particularly good companion for cabbages because it repels the cabbage white. It also works excellently as a border around strawberries because it deters the worms that feed upon them.

Lettuce should be planted with radishes because it helps tenderise and give them a better flavour.

Now you know all about companion planting you should go ahead and get your garden organized. The possibilities are endless, so if you study the properties of different plants closely you may even be able to discover your own sets of allies!

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