Creating a Perennial ‘Food Forest’ in a Polytunnel

The concept of a food forest or forest garden is one which has rapidly been gaining in popularity over recent years. But is it a concept which is often misunderstood. The word forest can be misleading, since the ecosystems often more resemble an open woodland than a dense forest in temperate climes.

When we talk about a food forest, we are essentially talking about a system that mimics a woodland or forest. But rather than creating a natural woodland or forest with entirely native species, the goal is to create an abundant and diverse ecosystem which delivers the food and other things we need.

A food forest or forest garden will be made up of a series of layers of planting – from trees at the top, to the shrubs, and herbaceous plants grown between and beneath them, to the tubers and bulbs and other elements of the rhizosphere below the soil surface. Climbers may also make their way up through these layers.

The layered planting means that you can fit far more food into a smaller area. This layering is one more way to make the most of your space.

Most food forests or forest gardens are outdoors, low-maintenance spaces. Once established, they typically include mostly perennial or self-seeding plants, and involve far less work than traditional annual fruit and vegetable gardens.

But creating a mini ‘food forest’ inside a polytunnel could open up a wide range of new and interesting options.

Why Create a Food Forest in a Polytunnel?

Creating a food forest inside a polytunnel could allow you to grow fruit trees and other interesting edibles that would not usually thrive in the climate where you live.

In the UK, this could mean that, even in an unheated polytunnel, you could grow Mediterranean fruits that you might struggle to grow outdoors successfully where you live. Peaches, apricots and nectarines, for example, typically only grow well in sunny and sheltered spots in the south. But with a polytunnel, they can be grown much further north.

You won’t have to grow more tender fruit trees in pots to carry indoors or under cover in winter, but will potentially be able to grow them in the ground. Dwarf varieties can be selected which will fit within a typical polytunnel structure.

If you heat the space within the polytunnel over winter, there is even potential to grow subtropical or even tropical trees and other plants.

Of course, growing undercover in a polytunnel (or large fruit cage) also means you may have more success in keeping fruits for yourself rather than losing them to the birds and other wildlife. So creating a food forest within a polytunnel could be a good idea even if you are growing traditional UK fruit trees in the space.

But why not just grow them on their own? Why grow them within polycultures of layered planting in a food forest?

Why Create Layered Planting Schemes Around Fruit Trees?

Fruit trees can have a wide range of issues with pests and diseases. But such problems are far less likely to occur where successful fruit tree guilds have been created. A food forest is, essentially, a series of fruit tree guilds joined together to create biodiverse and resilient systems.

A fruit tree guild is a group of plants which have been carefully selected to help the central fruit tree. They can help in a range of different ways. And can add or help maintain fertility. They can protect the soil, reduce moisture loss and enhance environmental conditions. Or they can play an important role in the system by attracting pollinators and other beneficial wildlife, or repelling, confusing or distracting pest species. They will also often provide an additional yield in their own right, as edible or medicinal plants, for example.

The goal is to look holistically at the planting, and at the system as a whole. You will boost biodiversity as much as possible and increase the number of beneficial interactions between all the different elements.

The plants you place alongside, below and around your fruit trees can be very important in making sure they stay strong, healthy and productive.

Getting Started Creating a Perennial Food Forest in a Polytunnel

The first thing to do if you want to create a perennial food forest in a polytunnel is consider the size of the polytunnel, and determine the best layout for your trees and shrubs. When thinking about the layout, you should also think about water at this stage.

Irrigation for Your Food Forest

Getting irrigation in place from the outset will be far easier than trying to retrofit it later on. Drip irrigation can be a good choice for your undercover growing area, since it uses less water than a sprinkler system and directs the water where it is needed.

Choose and Plant Trees and Shrubs

Next, decide which trees you would like to include. (Remember to make sure that you understand what size the mature trees will be and make sure they will fit within the space.)

Prepare the ground in the polytunnel ready for planting. Lay cardboard and mulch to suppress grass growth and weeds if necessary. And layer up organic matter to build healthy soil. Then simply dig the holes needed to plant each tree and shrub into the space.

Design and Plant Your Polyculture Guilds

Once you have chosen and planted your fruit trees and fruiting shrubs, this is when the really interesting work begins – layering up further planting and building the polyculture guilds around each tree.

Do your research and make sure that you find plants which will aid you, and aid the fruit tree in some way. Make sure you include plants for nitrogen fixation. And also dynamic accumulator plants to chop and drop to mulch around your trees and maintain fertility in the system. Think about which plants are in bloom, and when, and what insect life they will bring to the space.

Make sure that there is adequate ventilation, and that pollinators and other beneficial insects can get inside.

Remember, the design you create for your food forest will likely evolve over time. It is important to respond to successes and failures, and to use and adapt to change. The guilds you set up initially will likely be added to over time, as you discover new problems and plant new species to solve them.

Make sure you avoid leaving areas of bare soil. And that you continue to compost, and add more organic matter to replenish fertility over time.

As the food forest matures, yield will continue to increase and increase. You might be amazed by how much food and how many other resources a garden of this type can provide.

Do you have a food forest? Have you considered an undercover area to expand the range of plants you can successfully grow? Share your experiences in the comments below.