Permaculture Design: How to Perform a Site Analysis of Your City Lot

The first step to successful permaculture design is understanding your land. Performing a site analysis and assessment of your city lot will clue you in on sun and shade patterns, water trends, and soil quality.
By Eric Toensmeier
July 30, 2013

"Paradise Lot" by Eric Toensmeier with contributions from Jonathan Bates shows their journey using permaculture design to turn their barren city lot into an edible paradise.
Cover Courtesy Chelsea Green
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Paradise Lot (Chelsea Green, 2013) tells the story of Eric Toensmeier and Jonathan Bates turning the barren and run-down tenth-of-an-acre lot behind their duplex into what is not just another urban farm, but a "permaculture paradise" replete with perennial broccoli, paw paws, bananas, and moringa — all told, more than two hundred low-maintenance edible plants in an innovative food forest on a small city lot. The garden — intended to function like a natural ecosystem with the plants themselves providing most of the garden's needs for fertility, pest control, and weed suppression — also features an edible water garden, a year-round unheated greenhouse, tropical crops, urban poultry, and even silkworms. The following excerpt from chapter five, “Sun, Shade, Soil, Slope,” shows you how to assess your city lot for growing food, using the principles of permaculture.

You can purchase this book from the MOTHER EARTH NEWS store: Paradise Lot.

Permaculture design is about harmonizing your goals with the unique characteristics of the site. Rather than laser leveling and planting uniform rows, permaculturists strive to understand what’s happening on a piece of land: What is the overall pattern? What are the opportunities and limitations? What potential can be unlocked through regenerative land use? At first glance our backyard looked like a blank canvas — a raw slab of bad soil, uniform and monotonous. But as we studied the site, we discovered a different, far more complex (and complete) picture.

Sounds great. In order to get from here to there, however, it meant drawing a fairly tedious but truly worthwhile series of maps on tracing paper. Each map viewed the site through a different lens — soils, sun and shade, slope — each with an effect on a garden’s ability to grow and thrive. As we made the maps, we were observing, studying, and talking about each aspect, each of which presented us with a different vantage point from which to see what was happening on the land and a degree of focus that deepened our understanding. At the end of the process, we laid multiple layers of tracing paper on top of our base map to see a combined image illuminating our site’s less obvious secrets.

This phase of the permaculture design process is known as analysis and assessment. Analysis is about observing current conditions on a piece of land. In theory it does not presume to like or dislike, only to describe objectively. In practice this can be a difficult Zen exercise; an observation like “Norway maples cover much of the backyard” can quickly lead to feelings of frustration and discouragement. However, in the assessment you interpret the results of analysis through the lens of your goals for land use and evaluate the situation. For Jonathan and me, distancing ourselves like this helped, and we began to find peace with our towering Norwegian neighbors.

Permaculture experts say that you should spend at least a full year observing your site before deciding what to do with it. I had heard this many times but until now had never had the chance to try it for myself. We moved in in January 2004 and spent the year on observation and design. Along with drawing the maps, seeing the land in all its seasons gave us essential insights, not least of which was understanding the seasonal patterns of sun and shade, which provided the key insight that our design crystallized around.

Our future garden had some unusual patterns of light and shade, with different areas having distinct characteristics. The front yard faced southeast, and we could see immediately that it got great morning and early afternoon sun. This area was also protected by the house from cold winter winds, making it a warm, sheltered microclimate. Later we would find that this part of the garden had a longer growing season by a week or two on either end. In fact, much to our surprise, we were able to overwinter some plants rated at USDA zone 8 (hardy to 10 degrees F), though we are rated at zone 6 (hardy to −10 degrees F).

The alleys to either side of the garden had close to full shade year-round. On the south side this was courtesy of a twenty-five-foot arborvitae hedge that eliminated the possibility of sunny windows or a south-facing attached greenhouse. To the north the house itself provided heavy shade for most of the day almost all year. The backyard had an interesting pattern: the neighbors’ barn-sized garage on the south property edge cast heavy shade in winter on the southern half of the backyard when the sun angle was low. In summer the same area of our garden received full sun for at least six hours a day. The north side of our garden had the opposite situation. The winter sun’s low angle cut below our northern neighbor’s overhanging Norway maples, providing full sun in winter. But by midsummer the same area was in close to full shade from the maples.

We used some high- and low-tech strategies to determine sun and shade patterns. Jonathan took photographs out of the second-story window at different times of day and in different seasons. Dave Jacke came over with a handheld solar-finding device, which backed up Jonathan’s observations. (Of course today they have an app for that.)

Because of the high density of buildings and trees in our urban neighborhood, only one tiny area of the garden, at the far end of the backyard, had sunlight in both summer and winter. This insight, not obvious at first glance, was the seed from which our design grew. To meet our goals we needed a greenhouse, and the site provided us with the welcome constraint of only one possible location. The first colors had been dabbed on that blank canvas, and the rest of what we wanted to paint had to work around that.

It was quickly apparent that we had several distinct types of soil. The owners before us grew marijuana in the basement; when they went away for vacation they forgot to set the timer on their grow lights and burned the house to the ground. When we moved in, the new house had just been completed, including excavation for the new basement. The half of the yard directly behind the house was fresh fill; it was mostly bare and heavily compacted by construction equipment. The main ingredient was clay subsoil, but it also contained chunks of concrete, brick fragments, and pieces of asphalt. Together with rebar and plastic, these form a new mineral class that city gardeners call “urbanite.” So drainage was going to be a challenge, organic matter was absent, and we would have to address compaction. Mineral nutrient levels were low (phosphorus) to okay (potassium and calcium). The good news was that our soil tests indicated that the pH here was close to neutral, and there was no lead problem.

The other half of the backyard was made up of the remaining soil from the previous yard and is in some respects more typical of the oak forests that once covered the area. It was sandy and acid, with okay (potassium, phosphorus) to poor (calcium) mineral nutrients. There was at least some topsoil to speak of, which was a bit deeper under the Norway maples. It supported a somewhat weak growth of crabgrass, with some other urban weeds like ragweed and a feeble patch of Japanese knotweed. In Wild Urban Plants of the Northeast, Peter Del Tredici says of crabgrass (our dominant species): it “is remarkably drought tolerant and is common in trampled lawns in minimally maintained public parks and residential landscapes, unmowed highway banks and median strips, small pavement openings, and sidewalk cracks”; it is a “disturbance-adapted colonizer of bare ground; tolerant of contaminated and compacted soil.” Not exactly a ringing endorsement of our yard’s health. The fence lines featured typical urban, spontaneous vegetation like Norway maple and bittersweet, along with tattered forsythia and some feral red raspberries.

Our soil test also told us that the soil in this part of the backyard had lead — 454 parts per million, which the extension office at the University of Massachusetts considers a “low” amount. Jonathan and I were prepared for some lead, as it’s common in the Northeast’s older cities. If it had been worse, it would have been a major factor in our design. We would have had to cluster edible greens in raised beds or in our compacted soil areas and focus on fruits (which are lead-free, unlike roots and leaves) and support plants in the back half of the garden. As it was, the results of our soil test recommended we bind up the lead by increasing the pH, improving organic matter, minimizing tillage, and mulching — all things we were going to do regardless. The danger from dust in low-lead soils is greater than the danger from eating foods grown in them.

When we asked the neighbors about the history of the site, we learned several possible explanations for our lead problem. First, there used to be apple trees in the backyard. In the early 1900s, lead arsenate (lead with arsenic, a great idea) was a popular pesticide for apples.

Rounding out our trio of terrible soils were the side alleys and the tiny strips of soil surrounding the driveway. These were a patchy blend of sand and gravel fill with some low-grade topsoil in a few areas. Mineral nutrient content was low for most of the major and minor plant nutrients UMass tests for. At least the north alley had some vegetation: a few legacy ornamentals and a large tree of heaven.

Readers in drier areas where xeriscaping and other water-conserving garden techniques are more common may be surprised that we did not pay more attention to water. In much of the world, water is a critical limiting factor for any kind of agriculture. But our climate provides forty inches of rain a year, broken down fairly evenly month by month. During the twenty years I’ve lived in Massachusetts, I have rarely seen a month go by without at least some rain. In July and August we can have a few hot, dry weeks, but they are usually followed by torrential thunderstorms.

Jonathan and I had hoped to capture rainwater and use it to irrigate our gardens. At Wonder Bread our house had been at the top of a ridge, with the gardens down below. You could have filled a cistern or rain barrel near the house, run some drip irrigation through the garden, and let gravity do the work. Unfortunately, our new home had the wrong slope for this. The backyard slanted gently up from the house, the incline mild enough that we felt at the time that rainwater-harvesting earthworks like contour swales were not worth the effort and constraints they would place on our design. In retrospect, we wish we had given this more thought.

We identified issues other than water conservation and rainwater harvesting that would affect the success and productivity of our design. The first was aesthetic. Our backyard was barren and exposed. It seemed as if every house on the block could see everything that was going on there. Then again, there was no reason for us to go back there, nothing to draw our interest or even anything that needed doing. Northwest winds swept right into our backyard down a canyon formed by a row of houses.

Using a process Dave had developed for Edible Forest Gardens, we also studied our ecological neighborhood. Our job was to evaluate food, water, shelter, and other factors that impact populations of beneficial insects and birds that eat pest insects. Our neighborhood and yard scored poorly: no open water, few nectar sources for insects, and little plant food for birds. We also lacked the “lumpy texture,” or diversity of habitats and successional stages, that provide a healthy home for our pest-control allies like beneficial insects and pest-eating birds. There was some cover and habitat in the form of evergreen hedges and thicket-forming shrubs, as well as a narrow band of woods on the cliff across the street, though it had poor diversity, little understory, and none of the lumpy texture we want to see. Our overall rating was fair — one step up from a Walmart parking lot.

Site analysis also includes a look at legal restrictions (that is, what can you pull off?). Massachusetts is one of the most highly regulated states in the country, and Holyoke was no exception. Many sustainable practices, essential for the long-term survival of humanity, are currently illegal. So there were to be no simple composting toilets (even a high-tech, $5,000 model would have involved a drawn-out legal battle), no treatment and use of greywater in the garden (though this would reduce pressure on the city’s overloaded combined sewer and stormwater system), and no livestock except rabbits, which are considered pets.

Given the legal landscape, Jonathan and I decided to choose our battles. Because we wanted to trumpet our garden to the world by inviting people for tours, there were certain things we would have loved to do that simply weren’t going to happen. We were especially sad to close the door (so we thought) on chickens, as they were explicitly prohibited.

After our series of investigations into the property, we laid our single-issue tracing-paper sketches over our base map to see what the combined picture looked like. Sun and soil were clearly the most important factors around which we would build our design. The overlap of soil and light created a mosaic of patches with different conditions. We created a summary of our site analysis and assessment efforts that identified each of these distinct patches, characterizing their conditions, challenges, and limitations. We also noted our initial ideas about the suitability of different patches for our desired garden elements like compost areas, a shed, a pond, and vegetable beds.

Our front yard was a no-brainer. The moment we walked onto the property, we knew the front yard would be perfect for a tropical garden. Our site analysis confirmed that the southeast-facing, steep asphalt driveway, combined with the house, which would block cold winds, would create an island of Washington, D.C.–like climate. Although the soils were virtually sterile fill, this area had a lot to offer.

The alleys to the north and south of the house were both shady with bad soils. We knew we were going to have to use one of them as vehicle access so that we could bring building and gardening materials into the backyard, but we were not yet sure which one.

Our compacted-fill zone had several distinct patches. On the extreme north and south edges there were areas with full shade in summer; the shade, combined with terrible soil, meant these edges were particularly poorly suited for growing food. It was going to take some creativity to find a productive use for these zones.

The sunny parts of the compacted-fill zone, which represented at least half of our land with full sun, presented a more interesting opportunity. With work, we could improve the soil, but that area might be more suitable to a pond or raised beds. Further, our house had two back doors (one from each side of the duplex), and both opened into this area; logically, this would become our main social space. The house rose up from the backyard like a featureless cliff, and we wanted to visually anchor it to the garden.

In our areas with “good” soil (which meant that it was sandy, with some lead), we again had three divisions based on sunlight. The only spot for a greenhouse was right in the middle — the sweet spot that would have sun all year. Our sandy, acid, lead soil zone also had both sunny and shady areas in summer.

Now we knew some of what our site had to offer. We had spent a year observing it in all its seasons, analyzing its various aspects. We learned that it was far from the uniform empty lot it first appeared to be but rather a patchwork of islands with different conditions and different potential for helping us realize our goals. Its challenges were also apparent: shade, lead, compaction, poor aesthetics, and minimal habitat for birds and beneficial insects. But by understanding the challenges and some of the aspects that were never going to change, we began to see the possibilities as well.

What we needed next was an overarching vision to tie it all together, a layout that would harmonize with the patterns of the landscape. It was time for our first real experience with design — and to make choices we would have to live with for as long as we were there.


Excerpted from The Paradise Lot: Two Plant Geeks, One-Tenth of an Acre by Jacob Deva Racusin and Ace McArleton, and published by Chelsea Green. Copyright © 2013. Buy this book from our store: The Paradise Lot.


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