Forest gardening: growing a sustainable ecosystem

Guavas, kiwi fruit, Asian pears and plumcots are usually associated with exotic growing systems - not British farming. But a number of landowners are exploring how such crops can yield a sustainable source of valuable and nutritious produce on British farms.

Forest gardening is a low-impact growing regime that creates an integrated, self-sustaining plant network in areas within a broader farming system, and there are hundreds of such gardens across the UK. CLA member Simon Miles, an expert in the technique, operates one in Cornwall.

It is a commonly held view that our climate can only support a narrow range of crops produced from a conventional arable system, he says. “However, any farm type, on any scale, can be adapted to produce a wider array of valuable crops from strips of land, open fi elds, hedgerows, margins and woodland.

“Including edible nut-producing trees along with other food-bearing shrubs can transform land that has been scrub or for amenity into something productive.”

While soil type and local climate affect what can be grown, the UK has similar growing conditions to a broad group of countries from South America to Asia. It is possible to grow valuable crops here, including Jerusalem artichokes, almonds, pecans, feijoas and chokeberries.

Simon has spent the past 14 years on his 3.28-acre forest garden near Falmouth, determining which plant types suit individual climates, soil and growing systems. He passes on that knowledge to study groups and via a consultancy to farmers and landowners.

While agroforestry is generally a large-scale setup, a forest garden is likely to be smaller but with more species. The establishment and planting regime mimic the natural growth patterns of a jungle, where a wide range of plants with different needs have evolved to cohabit.

In Britain, these layered growing patterns are applied to temperate species in a forest garden system. Plants are chosen to meet a site’s climate and soil types and planted in a universal, seven-layered approach. The key is to decide what plants fit a site’s characteristics, whether that is its shape, dimensions, existing planting or soil type.

For example, a linear strip alongside an arable field might well support rows of pine nut-cropping trees as the basis for the seven-layered setup. This not only creates a windbreak for the arable crop, but its linear nature makes it easier to harvest nuts mechanically. Alternatively, rows or alleys of trees can be inter-planted with arable crops or pasture.

One farmer whom Simon advised opted for rows of trees with pasture in between them for grazing and forage production.

Multiple benefits are associated with forest gardening, including increased carbon capture, reduced fertiliser use, lowered nitrate leaching and a diversified income stream.

Introducing an acre of trees on a farm can capture as much as two or three tonnes of carbon a year. When trees are carefully sited and integrated within a structured forest garden process, the benefits can multiply.

“Including a fast-growing tree like an Italian alder adds structure to support fruit-bearing climbing plants in a forest garden system,” says Simon. “Dense tree branches also act as a windbreak, protecting arable fields from soil blow and emerging crops from strong winds.”

But the Italian alder, and some other trees, have a further beneficial role in a regenerative farming system: they fix nitrogen. The soil-borne fungi that develop around a tree’s roots distribute nitrogen in the soil. Additionally, mycelial growth associated with a tree can extend 50m into an adjacent field, contributing nitrogen for arable crops and improving soil structure.

According to Simon, it is possible to cut out artificial nitrogen applications altogether in strips, fields and spaces around the trees, which could save in fertiliser costs. The improved soil structure and nitrogen-fixing plants reduce nutrient leaching, too, so play a key role in areas where nitrate risks to watercourses are high.

The diverse plant range attracts a broad spectrum of wildlife, from soil-dwelling grubs to bird and mammal life. This enhanced biodiversity is a key government target, and Defra has set up a trial looking into forest gardens’ benefits.

Aside from contributing greater resilience to the growing system, forest gardening can also provide a valuable diversified income stream from previously uncropped areas.

Simon explains. “One well-established forest garden in Cornwall produced 50 boxes of kiwi fruit, harvested by two people in a single afternoon.”

The produce from Simon’s garden provides an additional income stream to add to returns from his consultancy and nursery. With a strong environmental selling point, including a dramatic reduction in food miles, demand is high for the produce, which is sold through local food outlets. Customers pay for the produce because of the environmental and nutritional benefits.

Trial work with nutritional value spectrometers has pointed to a potential fourfold improvement in nutrient content for the naturally-grown food.

Production timescales are encouraging, as many species such as Asian pears are fast-growing and can quickly yield a marketable fruit crop, says Simon.

“Typically by the third and fourth years, growers are excited about production levels, and by the fifth and sixth have to scale up the marketing process,” he adds. This is all extra food, produced at low cost, from a system that helps the environment.

Simon says: “We don’t know what the future will bring, but climate change, political upheaval and the war in the Ukraine have all shown that food supplies are vulnerable.

“While it won’t solve these issues now, forest gardening can produce food from previously uncropped areas, using sustainable techniques and so must be part of the long-term solution.”