Sustainable gardening is based on ecological principles. When we consider the home garden as an ecosystem, we develop the habit of observing patterns in nature and then look for similar patterns in gardens. Mature organic gardens, like natural systems are complex and rich. One of the goals of sustainable gardening is catching and holding resources.
Always start with the soil— enhance and maintain soil fertility by adding organic matter, so the existing soil microbes can thrive and flourish. Even a degraded site can develop a balanced ecosystem over time as the organic matter decomposes and forms humus. When the microbes of the soil web die, their decayed bodies act as slow-release fertilizer for garden plants. Focus on fertility includes compost, planting nitrogen fixers and other cover crops, adding manure, and growing plants that produce mulch.
We create more resilient gardens when we make connections with all of nature. Select plants that provide habitat for native insects, birds, and animals that can function together in a food web, as part of the home garden ecosystem. Layered gardens include trees shrubs and herbaceous plants that invite more beneficial visitors. The food web becomes more involved as rodents, snakes, and predatory birds engage.
When we design by grouping plants with similar environmental needs together there is less maintenance. Port Townsend’s mild wet winters and mostly dry summers are known as a Mediterranean climate. Native plants and plants from similar climates around the world, including Australia and New Zealand, offer many drought tolerant choices. Woody plants with edible fruits can be planted with an understory of perennial and annual herbs and edible flowers. Remember that perennials and annuals are more work than woody plants, so make sure they serve many functions!
Healthy, well-rooted plants withstand environmental stress caused by weather and poor drainage, and develop better resistance to insect pests and diseases. Planting in beds or mounds edged with paths makes a garden more inviting and eliminates the need for grass.
Gardening to the scale of the property lets us enjoy the intimate small garden or work with generous proportions of larger gardens to include the sky as part of the scale. Larger beds with masses of plants create bold simple patterns. Broadleaf evergreen shrubs and small trees can form the structure or bones of the garden. Strategic placement of flowering perennials and annuals allows us to enjoy the color with less work.
We built the pile one layer at a time, like a huge sandwich: Alternating dry material with green material, then a layer of soil. Another way to look at it is layering nitrogen-rich material with carbon-dense matter and then another layer of soil and or compost. We made the pile large enough to create an insular mass for the microbes to thrive. In the tropics 3 foot by 3 foot by 3 foot works. In temperate climates increase that to four-foot all around.
After lunch we came inside to review the soil food web and the basics of making compost.
If you explore a forest floor below the leaf litter, you find humus, the result of an entire soil food web. Compost is a way to speed up the process by providing the decomposers—soil bacteria, fungi and invertebrates with all the nutrients they need. We work with microbes when we make bread, yogurt, or sauerkraut. Compost is messier and larger but is similar in that we are creating an environment for microbes to thrive and directing their behavior to produce a product we want.
The building blocks of compost are nitrogen-rich material for strong bodies, carbon-rich material for organisms to energetically reproduce, air so the pile stays aerobic and doesn’t go putrid, water to hydrate to microbes, and soil or aged compost to inoculate the pile with organisms.
Compost enhances the garden in so many ways:
It reintroduces soil microbes to soils that have been damaged by chemical fertilizer and pesticides.
It improves the soil ecosystem and encourages beneficial microorganisms that protect plants from pathogens while soil fungi bind with and filter out toxins.
Compost prevents soil erosion by improving soil structure. Soil rich in organic matter is more porous; it allows air and water to move and be held, it has good tilth.
“Feed the soil and the soil feeds the plants,” is a famous Alan Chadwick quote I learned years ago. Compost feeds soil microbes that in turn release enzymes and hormones that promote healthy plant growth. Decomposing organic matter releases nutrients. The dead bodies of microbes act as slow-release fertilizer, providing nutrients over time.