In permaculture gardens, plants are not placed in mono-cultures – large areas planted with just one type of plant. Rather, polycultures are created, with a number of plants all of which can be beneficial to one another in a variety of different ways. As in a forest, polycultures are tiered or stacked systems, with trees or larger plants underplanted with smaller herbaceous ones, and ground cover plants. 

While we tend to think more about creating polycultures when planting perennial systems (such as forest gardens, orchards or herb garden beds), we can also think about creating polycultures in our vegetable beds, where we grow our annual crops.

What is a Polyculture?

A polyculture is more than just several plant species grown together. A polyculture is a collection of plants that function together as an ecosystem, like the plants in a forest, which interact and aid each other in a wide range of different ways, or merely co-exist happily. Creating polycultures in your planting schemes is all about maximizing the number of beneficial interactions that exist there. 

Why Create Polycultures?

There are a number of different reasons why we may wish to plant different types of plants in the same area. Some of the reasons involve the health and well-being of the plants themselves, while other reasons are to do with increasing yield and benefiting you, as the gardener. In terms of plant welfare, first, creating polycultures can:

• Add to nutrients in the soil (nitrogen-fixers and other dynamic accumulators, cover crops & green manures to chop and drop etc..)
• Protect the soil (through balanced nutrient uptake, increasing shading and reduced moisture loss etc..)
• Protect individual plants from temperature extremes (through shade provision.)
• Reduce pest problems (though confusing or repelling certain pests, or through attracting beneficial predatory species.)
• Help ensure good pollination (by attracting pollinators.)

Since plants are better provisioned, healthier and more resilient when aided by companion species in a polyculture, yields from your annual growing areas can be higher than they would be in a traditional mono-culture growing system. 

How To Create A Polyculture Planting Scheme for Annual Crops

By studying the characteristics of certain plants, we can determine which other plants we should place nearby. Understanding the needs of the plants you wish to grow, as well as understanding the climate and conditions were you live, is a good place to start when creating a polyculture planting scheme.

Intercropping

The simplest polycultures may consist of just two or three plant types. Simple polycultures of this type are sometimes referred to as 'intercropping'. Gardeners may talk about 'intercropping' cabbages and lettuces, for example, to make the most of the space and time available. This intercropping is a form of polyculture planting.

Layering

Those who hold to permaculture ideas and ideals, however, will often go further when creating their polycultures, with both perennial and annual crops. Permaculture growing areas will often incorporate the ideas of 'forest gardening' – even when talking about annual crops. In annual vegetable beds, you will not find as many layers as you would do in a true forest, but by creating layers of planting in a polyculture, you can mimic the forest system to a degree and can benefit from the beneficial interactions that occur between the various plants. 

Layering plants is not only about creating a series of tiers of layers that create shade and create a range of other beneficial interactions. It can also be about making the most of the space throughout the whole gardening year. We can layer in time as well as in space by, for example, sowing fast growing radishes with our parsnips, or other slow growing plants, so as to get an extra yield before the main crop is ready to harvest.

Guilds & Companion Planting

In a forest, you may often find that certain key species are aided by the plants that surround them. You can enhance this effect by planting specific species for the aid that they can provide. These collections of helpful companion plants are sometimes called 'guilds'. Understanding companion planting will help you determine which plants to grow together in your annual polycultures.

Companion planting is often an inexact science and there is not always sufficient research to explain why certain plants seem to or demonstrably do better when planted with others. Polytunnel gardeners will soon find that certain combinations of plants will work better than others, and many will recommend certain combinations that, as yet, have no scientific evidence to back them up. Still, it can sometimes be a good idea to listen to the empirical evidence and to take an investigative approach to creating valuable combinations and increasing the range of beneficial interactions. 

Sometimes, companion plants will aid others around them simply by enhancing the environment. This enhancement might, for example, be in the form of shade provided to moisture loving plants, which slows the rate of moisture loss from the soil and helps to prevent plants from bolting in warmer weather. Some plants offer more sophisticated aid to those around them. For example, anise is said to encourage better essential oil production in nearby herbs. 

Dynamic accumulators help other plants by gathering nutrients that can then be made available in the soil. Dynamic accumulators include deep rooted plants such as borage and comfrey that can be chopped and dropped to provide nutrition to neighbours, and nitrogen fixers such as peas and beans.

Another way in which some plants can be good companion plants is in helping with pest control. Some herbs and flowers will give off scent which will confuse or repel common pests in your annual growing areas. Others will attract beneficial creatures such as predatory insects, which will eat pests and therefore help to keep everything in balance. Other good companion plants will attract pollinators and so help make sure that fruit set correctly and everything continues to provide its valuable harvest as it should. 

By practicing polyculture planting in annual crop growing areas and other organic gardening practices, we can ensure that we can continue to grow crops year round year after year in a sustainable way that will work for a long time to come.