PHOTO: Dave Boehnlein
January 19, 2018
Say all the good things you want about farming—even organic farming, even “sustainable” farming—but a field of production agriculture isn’t exactly natural; it doesn’t mimic nature. When you’re truly in nature, you don’t find bare soil, straight rows or plants growing outside of their natural habitat. You find something more like what can be achieved through a food forest or edible forest garden, which are design concepts often used in permaculture and natural-garden building.
“An edible forest garden is a garden that is based off the model of a forest in nature rather than an ag field,” says Dave Boehnlein, a principal at Terra Phoenix Design and education director at Bullock’s Permaculture Homestead in Orcas Island, Washington. Food production might be one goal of this growing system, but medicine, pollinator habitat, erosion control and more can also be achieved. The diversity of plants, their traits and their functions mean a stronger, healthier ecosystem than what you find in a typical, simple food garden. Food forests take a lot of work to become established, but as they mature over time, they require less maintenance.
To build a food forest, you don’t need acres and acres—you can grow as many as 300 species on a 1⁄4-acre lot, according to Dave Jacke, founder of Dynamics Ecological Design in Montague, Massachusetts. In fact, smaller might be better, so you can enjoy establishing and maintaining your forest garden. Food forests are possible in cities, as evidenced by the Beacon Food Forest in Seattle, and even on a floating barge—if you happen to have one of those around—such as Swale, a project in New York City.
A food forest, like a wild forest, has layers upon layers of vegetation and soil compositions as well as varying density, plant patterns and diversity.
“The whole idea of food forests, in general, is mimicking an ecosystem,” says Jacke, coauthor of Edible Forest Gardens, Vols. 1 and 2 (2005).
Among permaculturalists at large, the common architecture of a food forest has seven layers of vegetation; however, not all permaculturalists agree. Jacke argues that the food forest has five elements of architecture, and the oft-recognized seven layers of vegetation is just one of those elements.
“People have a tendency to oversimplify, but ecosystems are very complex,” he says.
Jacke sees the architecture of the food forest broken into:
- the seven layers of vegetation, which is the focus of this article
- the horizons of the soil, which relate to the physical properties of each soil layer
- density of vegetation
- patterning of vegetation
- diversity of organisms
This is rather complex, as Jacke points out, but if you’ve spent any time in a forest in nature, you can easily picture and make sense of the presence of these elements.
Perhaps the simplest to conceptualize—and therefore the one most focused on in permaculture design—is the layers of forest vegetation.
“There can be as many layers as the designer wants or wants to perceive,” Jacke says. “‘Layers’ are a human concept we project onto the ecosystem. How many layers you design depends on your perspective and needs and site conditions.”
These layers—while fluid, as Jacke points out—are: tall-tree, low-tree, shrub, herbaceous, ground-cover, vine and root.
This is the canopy of trees in your food forest. Choosing the right species for this layer can be tricky.
“When you’re putting in your tree layer, increase spacing by 50 to 100 percent as compared with conventional orchard spacing,” says Boehnlein, who co-wrote Practical Permaculture for Home Landscapes, Your Community, and the Whole Earth (2015). “Even when the trees get full sized, light will still get to the bushes you planted in between.”
As many as 90 percent of the food forests Boehnlein has seen are too-tightly packed in their design.
“People assume that what they’re supposed to do is jam stuff together,” he says, but the opposite is true.
Along those lines, when choosing canopy trees, think about how tall these trees will get and how that will affect your food forest in years to come. Boehnlein mentions Martin Crawford, author of Creating a Forest Garden (2010), who doesn’t include large nut trees in his food-forest designs. Boehnlein loves chestnuts and walnuts, but they’re forest giants.
“They take up so much space,” he says. “If you want to grow them, grow them as their own grove.”
Trees naturally feed the soil as they lose their greenery, in addition to all of the other functions they offer to a food forest.
Canopy Trees to Consider: Think about mulberries, persimmons, cherry trees and pine nut species for human and animal food; Amur maackia, acacia and black locust as nitrogen fixers and insect attractants.
The understory layer of trees might be dwarf varieties or simply species that don’t grow too large. If you don’t have a big area for your food forest or you don’t want to deal with mammoth trees, your low-tree layer might be your canopy-tree layer by default.
Consider the pest and disease issues presented by the plants you select, especially in the understory tree layer, where too-little airflow and sunlight can become an issue. Fruit trees are a natural fit for a food forest, but the health and production of some fruit trees—apples, peaches, plums and apricots—might require more air and light than a dense food forest allows.
Depending on the disease, fungal and pest pressures in your area, Boehnlein suggests putting susceptible species elsewhere or adjusting your layout: “If you have a food forest that tops out at 12 feet, then these lower trees make a lot of sense.”
Alternatively, you could put taller trees to the north and lower trees to the south—if your garden is located in the northern hemisphere—so everyone has a better shot at getting the conditions they need.
Take Boehnlein’s tree-spacing suggestion to heart here, too.
Understory Trees to Consider: Look into pears, figs, pawpaw, citrus, coffee, olives and loquat for food; crabapple, hazelnuts and hawthorn as wildlife attractants and edibles.
In this layer, the sun or shade tolerance of plants is important.
When placing shrubs, consider the great amount of sunshine they will
receive when the food forest starts—the shrubs will often be taller than
the tree saplings, after all —
as well as the increasing amount of shade they’ll have as the whole system matures.
Shrubs to Consider: Mull over blueberries, raspberries, currants, elderberries and gooseberries for food for humans and wildlife; goumi and pea shrubs for food and nitrogen fixation; serviceberries and nanking cherries as insect attractants and food; sweetgale to fix nitrogen in the soil and attract pollinators; woody herbs such as rosemary and lavender, which attract pollinators and offer food and medicine, are shrubs, too.
Herbaceous plants in a food forest are nonwoody plants—usually perennials or plants that reseed themselves. Annuals can also be included, but part of the appeal of a food forest is its regenerative abilities and the reduced amount of effort required as time goes on.
Sun and shade requirements are important in this layer, too. Sun-loving plants can find a home on the edges of the food forest, especially, where they won’t be as shaded by the taller layers.
“There are dozens upon dozens of medicinal species and species that attract beneficials or improve soils or act as ground covers to inhibit weeds,” Jacke says. “Much of the diversity of ecosystems and forest gardens is actually in the herbaceous layer.”
Herbaceous Plants to Consider: Ponder comfrey, borage and mullein mine minerals from soil depths, break up the soil with their large tap roots, can be harvested and composted for additional soil improvement, and offer medicinal uses; nettle—stinging and stingless—mines minerals and provides food and medicine; sorrel, parsley, banana, rhubarb and asparagus offer food.
Plants that stretch and cover the soil fall into this category. The ground-cover plants out-compete undesirable plants so that you—rather than your weeds—are in control of the plants in your edible forest garden.
“When you disturb an area by planting your food forest, it is important to immediately plant something else (or mulch heavily),” Boehnlein says. “Any bare soil will turn into weeds. Without a ton more work, this is your chance to establish ground covers you want instead of the default weeds.”
Boehnlein adds that you’ll probably need to mulch around ground covers to get them established, too, or the weeds will move in while you’re waiting for the ground cover to do its job.
“Often what I do is plant larger, clumping ground cover plants surrounded by thick mulch at establishment, but wait on some of the low, spready, herbaceous plants until a bit later,” he says. “This is especially important with shade plants. If you plant lily-of-the-valley at establishment, you will just watch it fry in the sun.”
Ground-Cover Plants to Consider: Contemplate clover and alfalfa for nitrogen fixing, pollinator and medicinal benefits; oregano and mint for food and medicinal properties; creeping raspberry, erosion control; and miner’s lettuce, strawberries and lingonberries as food for people, insects and wildlife. Nonliving ground covers are important, too, such as mulches and rocks, both of which might feed the soil and reduce erosion.
Using other members of the food-forest ecosystem, vining plants make their own climbing trellises and supports. You can add trellises, too—particularly if vining plants are opportunistic to the point of damaging other plants, such as a passionfruit vine taking over a mango tree.
“There is also a timing issue here,” Boehnlein says. “If you plan to have the vines climb in your trees, you need to get your trees established first, then plant your vines. Otherwise, the vines will just consume the young trees. Vines can also cause air-flow problems in areas with fungal-disease issues.”
Vining Plants to Consider: Evaluate malabar spinach, which offers food through the hottest weather, when other greens go dormant; muscadine grapes, kiwifruit and hardy kiwifruit for food for people and wildlife; nasturtium and passionfruit for food and insect attraction; any peas and beans, which might reseed themselves, for nitrogen fixing and food.
By nature, roots also have vegetative forms above ground, so some roots are also ground covers or herbaceous plants. Roots to be harvested should be shallow so that in their harvesting, the other members of the food forest aren’t disturbed.
Fitting in somewhere between the ground-cover layer and the root layer are edible and medicinal mushrooms.
“These No. 1 gourmet decomposers are pretty easy to grow, depending on the substrate available to grow them,” Jacke says. You can inoculate your soil and mulch with fungi spores or intersperse inoculated mushroom logs throughout your food forest. Jacke points out mushrooms are a great option for deep shade and steep or otherwise unfarmable land.
Other Roots to Consider: Reflect on ginseng, goldenseal and the cohoshes as medicine; horseradish as an edible and medicinal plant whose leaves offer living mulch; Jerusalem artichoke for wildlife, insect and human food; peanut as an edible nitrogen fixer; ramps as food; camas as insect attractant and human food; shiitake, turkey tail, pearl oyster, lions mane, garden giant and elm oyster mushrooms; the mycorrhizal biosphere exists within the root layer, too, and all of the diversity that you’re bringing into your food forest is contributing to its health and diversity.
What’s Right for You
The plants suggested in this article may or may not be appropriate for your own forest garden, depending on your location, climate, soil type, goals and more. Consider the cultivation and maintenance needs of each plant before you plug it into your food-forest design.
It seems that a food forest can provide everything you might need on your land, but before you go into full planning mode, look at the natural landscape of your area. If forest is a predominant ecosystem, a food forest could be right for your property. If you’re more in a prairie or desert, other permaculture-design options might be better, or your food forest might look more like a food prairie, food savannah, edible desert or food chaparral rather than a food jungle.
“A food forest is one kind of agriculture that is resonate with the idea of permaculture,” Jacke says. “It’s another tool in the toolbox.”
He points out it’s unexpected that the person who literally wrote the book on food forests is telling people that these systems might not be appropriate everywhere, but you can’t force nature. In fact, food forests revolve around doing just the opposite.
Just as in nature, every plant in a human-constructed food forest has one or more basic functions:
- Human Food: This is usually a primary function of a permaculture food forest.
- Soil Improvement: Plants and other natural elements can act as mineral accumulators and nitrogen fixers. They can halt erosion, break up heavy soils and more.
- Insect Attraction: Not just pollinators but also pest-predator and parasitoid insects are drawn to different plants, so a range of insect attractors with different blossoming schedules and flower structures are vital.
- Animal & Bird Habitat & Food Trees for birds to nest in, fallen fruit for your chickens to forage and places for other wildlife to nest are part of the whole picture of a natural system. These animals, in turn, offer fertilizer and pest control for your food forest.
- Medicinal Uses: Many plants that are delicious or that offer soil improvement also are traditionally used in holistic medicine.
Throughout your food forest, you should have a good cross-section of plant functions. “We’re looking at all the little pieces and putting them into an assembly,” says Dave Boehnlein of Terra Phoenix Design.