What is a forest garden?

A gentle introduction to forest gardening, edible layers, and the plants growing at Marston Forest Garden. By Jo Milton

Attending a special event at Marston Forest Garden, I was introduced to the fascinating concept of forest gardens — and to a whole world of remarkable edible plants, from onion trees and heartnuts to pignuts and loquats.

In the UK, the idea of forest gardens dates back to the 1970’s when Robert Hart became interested in the relationships between plants in natural systems like woodlands. Starting with a small orchard of apple and pear trees, Robert created an edible ecosystem by underplanting the existing mature trees with shrubs, perennials and ground cover layers. Visitors to Robert’s garden wrote this inspiring piece entitled ‘The garden of love‘ – it beautifully describes the garden as ‘green and lush’ and ‘dripping with fruit’ – a wonderful image.

The seven layers

Forest gardens typically include seven layers of different plant types to make efficient use of available vertical space to maximise harvests.

Canopy and low tree layers

The top two levels are made up of trees – both large and dwarf stock if space allows. If you are lucky, you may already have one or more fruit or nut trees on your plot or be able to invest in some mature specimens. The almond tree at Marston Forest Garden took until its fifth year to produce seven almonds. Failing that, it is worth planting young trees as your first step, so that you can reap the rewards of the canopy layer as soon as possible

On the plus side, you can grow some more sun-loving plants whilst your trees mature.

Aim to plant fruit or nut trees in winter, choosing varieties that suit your space: hazel for smaller gardens, walnut or sweet chestnut for larger ones, and dwarf, self-fertile or trained fruit trees for small gardens. Apples, pears, plums and cherries are reliable UK choices, while figs, peaches, apricots, mulberries and quinces are good options for something more unusual.

Shrub layer

There are a multitude of currants (black, white, red and gooseberries) suitable for a UK climate, including some more unusual hybrids. I’ve added a jostaberry to my patch, a cross between blackcurrant and gooseberry. There are now many thornless currant and berry varieties, although that might also make it easier for the birds to get their share. To maximise fruit production, currants usually require some pruning – read how in this guide - or leave them to become a little unruly.
Autumn fruiting raspberries are a great option to grow in clumps; as a woodland plant, they will thrive in semi-shade. Cut stems down to ground level in winter, and new canes will grow and fruit the next year. I also have a chokeberry, which does well in wetter ground and makes good jam. Gojiberries are increasingly popular, producing a plentiful supply of red berries to enjoy raw, cooked or dried.
At Marston Forest Garden, two Szechuan peppers (pictured) form part of the shrub layer. This extremely hardy deciduous shrub has red fruits, the outer husks of which are used as a peppery and fragrant spice. The aromatic leaves can also add a spicy, citrusy flavour to cooking. In late spring to early summer, they produce clusters of cream flowers. When autumn arrives, the red fruits ripen to reveal shiny black seeds (as pictured). They grow well in dappled shade, don’t need pruning and the leaves turn a stunning vivid yellow in autumn. The thorns are really the only downside of this interesting plant.

Herbaceous layer

This layer is full of perennial herbs to stimulate the senses, some of which overlap with the shrub and ground cover layers. From a near-infinite list, some examples are mint (of all flavours), lemon balm, lovage, sorrel, fennel, hyssop, marjoram and tansy. If you do have a sunnier spot, with well-drained soil, the Mediterranean classics sage, rosemary, thyme and lavender will thrive. Valerian is an interesting herb; its root has a soporific effect and can be used as a tea to aid sleep. Rhubarb is one of the most frequently grown perennial vegetables and is more shade-tolerant than you might expect. Grow early and late varieties to extend the harvest season.

Edible flowers combine with the variety of perennial leafy greens to add vibrant splashes of colour to summer salads. Culinary roses (pictured), bellflowers, chives (and many other alliums), nasturtium, violet, dandelion, salsify and mallow flowers can all be eaten raw.

Day lilies (Hemerocallis) are another delicious flower to try after cooking – fry or steam the fresh flower buds. They are tough, somewhat ‘thuggish’ plants that will spread over time into a large clump. As woodland-edge natives, they cope well with the shade of a forest garden.

Rhizosphere (or underground) layer

The rhizosphere includes root vegetables, as well as perennial onion (Welsh and Egyptian) and leek (Babington) varieties, fungi and mycorrhiza. Root vegetables typically grown on allotment and garden plots are biennial, but there are a number of useful perennial species. I have tried Jerusalem artichoke, horseradish and scorzonera, which also has edible leaves and flowers. Some of these plants have long tap roots, which help to break up compacted soil and draw nutrients and water from deeper ground.

Until my visit to Marston Forest Garden, I was unaware that you could grow your own peanuts in the UK. Confusingly, the groundnut is not a nut at all, but rather a member of the pea and bean family. They aren’t fully hardy and so may not survive winter in cooler regions of the UK, but wouldn’t it be amazing to grow your own peanuts!

Ground cover

One of the aims of forest gardening is to ensure that no bare soil is exposed. This helps prevent flooding and soil erosion, and hopefully reduces the number of plants in the wrong place (previously known as weeds).

In my own garden, I tend to let herbs like mint and lemon balm spread. I prefer to have masses of them that I can control by picking, rather than less appetising thugs like couch grass. No forest garden would be without alpine and regular strawberries (pictured). They can be left to ‘run’ and root where they can find a smattering of bare soil.

Vertical layer

Utilising the vertical aspect of any garden with naturally climbing plants and vines greatly supports efforts to be self-sufficient.

Grape vines, brambles, and hops are among the more common possibilities, but there are many others. I was once gifted a loganberry, a hybrid of blackberry and raspberry. The fruits are dark red and juicy – perfect for a summer pudding. Honeyberry is another edible climber I was introduced to in Marston. The fruits look like elongated blueberries, taste similar, and are full of antioxidants.

Wander and observe

With thanks to all of the land stewards at Marston Forest Garden, especially Anthony and Isobel, who guided us through this serene and enchanting edible landscape. Connections with people and nature are nurtured for current and future generations. To echo Robert Hart’s sentiments, the garden is transformed by love.

Marston Forest Garden usually meets on the second Sunday of the month. Check the Marston Community Growing website events page for the latest dates, times and details before going along.

Up close with a rose chafer beetle in the forest garden

Additional Resources

What is a forest garden? | Permaculture Association

The Garden of Love - an article on Robert Hart’s garden by Ken Fern of Plants for a Future.

Edible Flowers for the Permaculture Garden – Spiralseed

The Backyard Larder

Martin Crawford’s Forest Garden Video

Editor’s note: This guest article was originally written by Jo Milton and published on Replenish Oxfordshire after a visit to Marston Forest Garden, one of Marston Community Growing’s most distinctive spaces: a calm, layered, edible landscape where trees, shrubs, herbs, flowers and fungi grow together. With the author’s permission, it has been lightly refreshed and republished here. It remains a lovely introduction to forest gardening and to some of the edible plants growing at our site.