What is forest gardening?
Forest gardening is a way of gardening that mimics natural ecosystems. Through observation and study we learn the patterns and principles that make a living system resilient, self-replicating, productive, efficient and diverse. We then take these principles and apply them to our home gardens, orchards, hedgerows and wood-lots.
I think about forage gardening also as forage gardening or hunter-gatherer gardening.
What is the difference between forest gardening and regular gardening?
There is no ‘better’ method and they are not incompatible. Forest gardening is a long term approach to developing a particular piece of land with perennial plants taking the main focus, but annuals are still a key part of the process. Forest gardens are work and input intensive in the beginning, and become more about maintenance as they develop. The yields from a forest garden are often spread in smaller amounts over time rather than large seasonal harvests. The concept of ‘forage gardening’ implies that on any given day there are several things to harvest. The intention is to have consistent year-round yields. Forest gardening requires some adjustment to our eating habits so that we are harvesting and consuming the things that are in season.
Using micro-climates and niches?
A Niche (pron: nitch or neesh) in simple terms is an opening with favorable conditions in space or time for some organism to occupy. These specific favorable conditions are sometimes referred to as micro-climates. For example, a wetter micro-climate at the edge of flagstone in a pathway, or a shady, cooler micro-climate on the north side of a rock wall or building. Nature likes to fill unoccupied niches with some kind of living thing and does so as quickly as possible, often with things we don’t want, often called weeds.
In a forest garden we look at ‘weeds’ a little differently. First of all, ecologically speaking, any living organism is better than nothing living. Next we attempt to observe what niche it is filling and what functions it is performing. Also we find out if it has any useful qualities that we can turn into a yield. It is amazing how many “weeds” are edible with a high nutrient density, have medicinal qualities, or are performing key ecosystemic tasks like erosion control, soil building, or beneficial insect habitat. By indiscriminately eradicating weeds we are often creating niches for even weedier weeds to occupy. Annual weeds are nature’s pioneer plants and repair mechanisms. The more damaged the land becomes, the more thorny, toxic and tenacious the weeds become.
When observing natural forests and ecologies we find that almost all niches are filled, often with redundant species. When a tree falls, disturbing the soil, there are a host of light-germinating annual seeds ready to grow, or young shade-germinated trees ready to take advantage of the niche.
In our forest garden, any time we observe or create an open niche we attempt to fill it with something that is directly useful to us, or something that is indirectly useful to us by filling the needs of another organism in our garden.
8 Layers, niches in space
We can understand a fully functioning ecology by observing what fills all the niches in both space and time. In space there are 8 basic physical zones or layers that plants occupy:
- Canopy or over-story
- Under-story, smaller trees
- Shrubs, bushes
- Herbaceous plants
- Ground covering plants
- Rhizosphere or the part of the soil that is influenced by roots, below ground plants, and fungi
- Aquatic or under-water layer
When we design our forest gardens we can think about these 8 layers and evaluate how to fill all of them. Sometimes limited resources such as area, light or water require fewer species to be stacked into one area.
Niches in time
Openings in time can be observed most simply as seasonal changes. For example, when deciduous trees drop their leaves in the fall, cold tolerant ground covers can thrive. Time of day and seasonal changes present many opening and closing niches that we can put to use. Even in an annual garden we use these principles if we plant kale and other cold-hardy plants around our tomatoes to grow and fill in once frost ends the warm season crops.
Many of our local ‘weeds’ here in Western Colorado are adapted to germinate in the colder wetter fall, after summer harvest, when the ground is bare and exposed. They are able to go dormant across the winter and then burst out first thing in the spring when there is water available as snow melts and the ground thaws. We can effectively occupy these niches with cover crops such as winter wheat, rye and vetch.
Guilds & choosing plants
Guilds are functional, interconnected groups of plants & animals, also called a poly-culture. The concept of a guild draws from the ecological term ‘community’. A community is a collection of different species living in the same place and connected by the influences that they have on each other.
In a mono-culture external inputs are constantly required to maintain the system. In a poly-culture the idea is to place things together so that beneficial relationships are created. The needs of one element are provided for by the others around it. Energy and material is cycled within the system so that no waste is produced. The output of one thing is the input for something else.
There are many ways to design guilds and choose the plants that we will put together.
Observation & Native species
The most basic principle and foundation of the whole process is observation. We observe natural, functioning systems to learn what works and which species like growing together. If we see highly functional and productive patterns we can mimic those patterns and species in our own gardens. For example scrub oak, service berry and mountain mahogany is a high desert plant community. These three native shrubs form the main productive elements of some local ecosystems. High protein acorns, service berries and the nitrogen fixing mountain mahogany form the under-story with an occasional pinon pine growing in the over-story.
Our forest garden can mimic the patterns we observe in nature. In our home gardens we might select cultivated varieties of service berry, a sweet bur-gamble acorn cross, and substitute another native nitrogen fixer: buffalo berry. We continue to fill in the under story with a selected variety of fruiting prickly pear cactus, sand-cherry and yarrow.
Climate analogues & research
Climate analogues are places around the world with very similar climactic characteristics of the location we are designing for. Many of the opportunistic species that become weeds were introduced here from places with similar climates to here, for example Russian Olive and Siberian Elm. While we may not plant more of these species in our system, if they are already present they do have functional uses as a nitrogen fixer and coppice tree for fire wood.
However, there are many climate analogue species that are not weedy and are highly productive in this environment: apple, apricot, pear, mulberry, cherries, Nanking cherries, Siberian pea shrub, yellow horn, to name a few. We can use these species in our guilds as the main over-story plants and design around them.
Researching plant varieties that will work helps us come up with a larger list of possibilities to choose from. We may be confident some plants will work based on the experience of others, some species will be experimental as we observe them in our gardens.
We can start the design of a guild from a purely structural viewpoint. This is especially useful when designing for confined and limited spaces. We draw out the main over-story trees and then fill in the spaces with several under-story shrubs, down to herbaceous and ground cover layers. Once we have an idea of how many plants will fit into the area we can then start assembling lists and groups of plants that are of interest until we arrive at the exact choices we want to include.
How to establish a forest garden?
Depending on time, budget and available plant material we can approach the establishment of a forest garden in several ways.
Ecological systems develop slowly over time in waves of succession that move toward greater complexity.
For example, if we start in a desert with bare soil and little life, the first phase would be the very simple organisms such as lichens, mosses and bacteria that can live in harsh conditions. Thorny, sometimes toxic annuals often form the next phase of succession, defending their hold on a small spot of ground and keeping browsing or walking animals away. As organic material collects, micro-climates of slightly shady, or wetter areas form and build soil life, which may support insects. Insects attract birds, lizards, mice and other animals that may carry seeds. More complex life takes the place of the pioneers which are pushed to the edges where they can continue to “pioneer”, or as they are shaded out they drop dormant seeds that wait for soil disturbance and sunlight to germinate.
We use the principle of succession, but accelerate it with various techniques to speed the establishment process.
We can plant thick cover crops, nitrogen fixing pioneer plants and other mulch producing species to kick start the process. We will probably ‘chop and drop’ these plants, cutting them back to stimulate growth and dropping the cuttings as mulch on our target plants. The pioneers that we introduce in the beginning will be designed to be phased out as the system develops.
Adding mulches and organic material of all kinds simulates many years of natural leaf drop and organic matter accumulation. These mulches immediately begin to suppress the sunlight germinating annuals, as we fill that niche with cover crops, flowers, and other fast growing plants. Our main over-story and under-story plants can be introduced right from the start and pampered with extra water, compost, and protection from animal browse. The pioneers will be cut back repeatedly until the over-story plants take over.
Some sites need erosion control and several years of cover-cropping and fertility development to effectively support the over-story species. In the mean time, we can use the space for annual gardens, building soils with mulches, compost and cover crops around our main perennials.
Weed and grass competition can stunt young trees, so control measures are sometimes necessary. Sheet mulching, or mulch on top of cardboard or bio-degradable fabric, can be used to both control weeds and create a long term bank of organic material.
In general, perennial systems prefer a fungally dominated soil, while annuals prefer a bacterially dominated soil. Animal manures, active compost and fertilizers are beneficial to annual gardens, while our food forest will appreciate wood chips, straw, leaf matter and other chunky sources of carbon that will encourage a more fungal growth.
Earth works such as berms and basins, terraces, and swales are often used prior to establishment to help create favorable micro-climates for a forest garden.
Maintenance & work
The maintenance of a forest garden takes different forms as the garden matures. At first it is establishment, gathering species, creating a nursery to propagate, trying species, drip irrigation, mulching, and earthworks. We next move into a phase of extending as we find out what works and spread those successful patterns into larger areas. We will be taking cuttings, continuing nursery propagation, gathering and scattering seeds, and cutting back pioneers instead of bringing in mulch. In the later phases as the system matures, we will start observing nature take over, new species will show up by themselves, we continue to chop and drop, pruning, harvesting, attending to spots that have gone weedy, introducing shade tolerant species in the under-story.
Issues & Challenges
Weeds, pests, disease, competition, harvest.
Edible Forest Gardens – Dave Jacke and Eric Toensmeir
Plants for a Future. pfaf.org
Gaia’s Garden – Toby Hemenway
A quick list of guild species:
- Buffalo Berry
- Sea Buckthorn
- Nanking Cherry
- Choke Cherry
- Italian Dandelion
- Crown Vetch
- Clumping Onions
- Thornless Blackberry
- Arctic Kiwi
- Scarlet Runner Bean