Forest Garden Design
By Jana Powell , Colorado Master Gardener in Gilpin County
There is a growing trend globally towards sustainable or ecological landscaping. The idea is to make everything work together productively in order to minimize energy input to achieve the most efficiency. The principles of sustainable landscapes combine plants, animals, insects, water, structures and people into symbiotic relationships to help each other survive and thrive. Topography, microclimates, sectors, companion planting, proper plant placement, nutrient recycling are all used when designing sustainable gardens. Many landscapes are designed to be separate ‘islands’ from the real world creating monocultures and high maintenance landscapes that usually require many chemicals to grow. Once established, sustainable landscapes are mostly self sufficient.
Sustainable landscapes are design intensive. More planning is put into the original design up front with careful plant placement to ensure a long healthy ecosystem. Sadly, many landscapes installed will need to be ripped out and renovated within a short time of installation, because of declining health due to poor design. A good sustainable design is created to be diverse. When one element fails other elements will help the system survive because of the planned diversity. Ecological gardens look different than a traditional garden…they are evolving.
Forest gardening is becoming a popular sustainable way to garden.
Before you begin to design your forest garden you will want to observe the characteristics of your site. Some observations you may want to consider are;
1. Slope-the steeper the slope will affect wind speed and water retention. Use wind breaks, such as penetrable deciduous trees in a boomerang shape. Design a windbreak based on succession starting with smaller plants. Use hardy species with deep roots, fast growing, self mulching, and nitrogen fixing abilities. One of the most important considerations when designing on a slope is to know where your water is coming from. Use swales for retaining water and terrace to prevent water erosion. Gentle slopes 15 degrees or less are ideal for planting.
2. Aspect/orientation- be aware of the direction that a slope or future landscape faces. Are there any thermal zones, or cold sinks to consider? What are the microclimates?
3. Sectors- sun, rain, native animals, wildfire. How does light move across your landscape during the day and at different times of the year? How does water flow. What animals will be grazing across the landscape, etc.?
4. Make Connections- make connections between your problems and assets. What are the primary pollinators and when do they arrive and leave? Observe plants that like to be next to each other.
Here are some good principles to keep in mind when you are designing your garden
1. How big will your plant get when it is fully matured.
2. Use pathways and rock terraces for thermal mass.
3. Define your planting areas by using guilds and special categories.
– A guild is an assembly of plants and animals that benefit each other. Guilds combine natives, edibles, medicinal and culinary herbs, pest control, companion and wildlife plants into a mutually beneficial group. To establish a guild identify a central element, usually a large tree that can provide food, shade and habitat. Consider this elements needs. What pollinators, sun, and water will it need to grow and provide shelter for your garden? How much wind can the plant withstand? When building a guild keep in mind diversity. Use dynamic accumulators with long reaching tap roots that mine nutrients from deep under the soil surface for other plants to use. Design with plants that act like living mulch to protect from soil erosion, keep moisture in, as well as distribute nutrients when their leaves break down in autumn. Certain bulbs and herbs can break down hardened soils. Always use nitrogen fixing plants that take nitrogen from the air and release into the soil.
4. The ecological garden is a partnership between plant and soil. Plants cultivate the soil and feed microorganisms with their roots. Plants help to balance temperature, as well as water. Microorganisms break down nutrients in the soil for plant food. You will want to use a high quality compost to establish this community of plant and soil. After the soil in your garden has become self sustaining you can cut back on the compost. Avoid digging and tilling, as this disrupts the natural symbiotic fungi relationship in the soil that assist plants with nutrient and water uptake.
5. Start small- try a 30×50 section before expanding.
The design of a forest garden mimics a natural forest. A forest garden typically has seven layers.
1. Canopy-larger trees(Evergreens)
2. Mid-story-smaller trees (Rocky Mountain Maple, Serviceberry, Red-berried Elder, etc.)
3. Shrub(Woodland Rose, Golden Currant, Boulder Raspberry, etc)
4. Herb (miner’s lettuce, comfrey, dill, etc.)
5. Ground covers (cloves, kinnikinnick, strawberry, etc.)
6. Root (garlic, onions, potatoes etc.)
7. Vines (Silver Lace Vine, Clematis, etc.)
Stacking layers allows each species to gain full potential from the resources around such as, water, light, nutrients and space.
Creating a healthy ecological garden means that eventually through succession, and establishing a diverse soil community you will not need to add as much fertilizer, labor and water in the future. By implementing just a few principles now, you will begin to encourage the landscape toward sustainability. The process is meant to be slow, to assure its sustainability and to achieve the gardener’s ideal environment that fits their unique style.