Urban Permaculture

Earlier, in March 2010, I held an Introduction to Permaculture course, and one of my students came forward eager to change his front lot into a productive edible landscape and design through permaculture principles. On a cool June morning, the students from the course converged on Terry Blume's house for a day of hands-on work. The goal: to change a vacant muddy front lot into a thriving permaculture garden!

In permaculture design, the design directive is to pacify energy and resources as they pass through the landscape, effectively slowing then down so they can be harvested into useful storages and functions.

Anywhere on this planet, the limit to life is water – no water, no life! In Calgary, we get only slightly more than 500 mm of rain annually, so not very much relatively. When it does rain, however, it pours. So naturally, taking the permaculture approach to landscape design means designing water storage into the system, which is the same as designing life into the system.

Therefore, the question facing us on this project was: “how do we capture and store rain water on this site for as long as possible so that all of it can be used before it drains of site?” It's very difficult to capture and make use of something if it is moving fast and uncontrollably, so we must first slow it down and pacify it. Water flowing uncontrollably from rain gutters will quickly erode away soil, and what's worse, that's water you could be using for your plants, instead of having it uncontrollably flow off the site.

So to start storing and using rainwater, we first needed to slow it down and pacify it. There's no better place to store water than in the soil itself. This is why whenever you go into a woodland, you'll generally see more moisture. Forests are really good at taking rainfall and putting it into the ground.

The Swales

There's an excellent method available for helping water from your roof (or other catchments) infiltrate into the soil, called the swale. A swale is a level trench on contour that functions to hold water long enough for it to infiltrate and wick into the soil (more on passive water harvesting here). So that's exactly what we did as a first step in designing the garden. The lot gently slopes toward the street, and next to it is a walkway that is constructed to three stepped levels (see Figure 1). So we opted to change the general slope into three flat planes that harmonized with the steps, as not much work was required.

Next, we decided on how to place the swales in the garden. Knowing that one of the worst things one can do to soil is step on it, we quickly saw the opportunity of using the swales themselves as accessways for getting around the garden. We created a design plan (Figure 3) where our swales were spaced double-arms reach from each other and the edges of the garden.

With the design completed beforehand, the team of students went to work and dug out the swales. Using a water level (Fig. 5), we levelled the bottom of the swales so that they were perfectly level. Swales are designed store water and not transport water, so that water has time to infiltrate into the soil to the plants' roots.

After they were dug out, we installed perforated flexible pipe (commonly called weeping tile) into the bottom of the swale, and then filled the swales to the top with pea-sized gravel. The reason to use gravel is to provide a permeable material for water to flow in the swale, and it makes a nice pathway material once full. It also stabilizes the walls of the swale trench. The function of the weeping tile is simply to offset the amount of gravel needed to fill the swale.

Sheet Mulch

The existing soil on the site was almost 100% clay, and was void of any biology. There's a big difference between soil and dirt. Soil is one of the most diverse and connected of ecosystems on earth. Plants thrive from a beneficial relationship with fungi and bacteria. When no biology exists, then plants cannot thrive, which further disables the conditions for soil biology to survive (Read the Story of Soil here, written by Verge Permaculture). Our task was to reset the ecology of the soil to return biology by importing biological materials and activate a composting process into the ground itself. What we did was put in a sheet mulch, which is a layering of nitrogen-based and carbon-based biological material. Specifically, we used these layers, but this is not written in stone, and will depend on the availability of the materials:

You can speed up the soil process by more than 100 times faster than it normally would in ecology using this method.

All this work could have been done with chickens using a chicken tractor. Chickens inherently do many useful things. They like to scratch, which aerates the soil; they turn household scraps into poop that adds fertilizer; and they eat pests. A chicken tractor is essentially a mobile coop that you move across a piece of land where you wish to start a garden. As you move the chicken tractor, the site receives all the soil-building services that is achieved by the sheet mulch, but for a fraction of the energy spent. Soon enough, chickens will be legal in Calgary!

Planting

The goal of this project was to create an edible landscape that is both productive and beautiful, and just at importantly, involved a minimum of work, time and energy inputs for a maximum amount of production and yield. We've already taken care of many of the needs of this garden already, through soil building

(via the sheet mulch) water and accessways (via swales). Still, some other needs include pest management and fertilization. This is where strategic use of beneficial planting assemblies come in.

A pest problem is a pest-eater deficiency. We designed this garden to actually provide habitat for pest eaters by inter planting flowers and a general diversity of plants. For example, let's say you were a bug that really likes wheat. How better can the situation be for you if everything you like is growing in one place? It's no wonder that “pests” are an issue.

For every “productive” plant, such as tomatoes or peppers or raspberries, about 10 “unproductive” support species are planted. These support species have very important function: to build soil. We planted a “cover crop” of field pea on the edges of our garden beds. The field pea fixes nitrogen into the soil, provides shade to the beds, and returns minerals and nutrients to the growing beds.

Knowing what kind of edible plants we wanted in this system, we developed a companion planting scheme for the different garden beds, which are numbered here:

Based on some research of companion planting literature, we decided on the following plant assemblies for each of these beds:

The plants mature

Once all the seedlings and seeds were planted and watered down thoroughly, our work was done. In about 6.5 hours, what we started with a blank lot was turned into a productive edible landscape of which will require a minimum of time and energy to maintain.

As this garden matures, its ability to store water will increase, because the more fertile its soil becomes, the more it will be able to sponge in water from the swales. Essentially, we created an upward spiral, where the conditions for increased food production lead to increased soil fertility, which leads to increased water retention, leading to further increased soil fertility, leading to increased food production. The cycle just exponentially increases until a mature state of production is achieved. In permaculture, we call this a food forest.

This project is just a little example of how we can use design to begin a situation where the benefits are exponential through the passage of time. Everything on this planet is patterned in a

way that exponentially creates opportunity for life, and all we need to do is embrace these patterns and use it as a guide for designing. Everything from gardens to communities and business planning can benefit from a permaculture approach to design.