THE SUSTAINABLE GARDEN by Owen E. Dell
This article originally appeared in Pacific Horticulture magazine, Winter 1998. Reprinted by permission.
Part Two- IMAGINING A BETTER GARDEN
Imagine a garden that rarely needs pruning, watering or fertilizing. One where natural controls usually take care of pest problems before the gardener even becomes aware of them. A peaceful garden where the sound of blowers, power mowers or chain saws never intrudes. Imagine a garden that also serves as a climate control for the house, keeping it cool in summer and warm in winter, a garden that traps rainwater in an attractive streambed to deeply irrigate the trees and recharge the ground water, one that provides habitat for wildlife and food for people. Imagine a garden that truly works. This is the sustainable garden, not barren or sacrificial, but as lush and beautiful as any other without all the struggle and waste. Yes, it is just that simple.
Southern California landscape consultant Randall Ismay has calculated that 80 percent of the total cost of a garden over its lifespan is maintenance labor and materials. Only 20 percent, then, goes into its design and construction. That is often partially attributable to unrealistic limitations on the designer’s time and corner-cutting on the installation, but for the most part, that 80/20 split is due to poor design that creates a permanent maintenance burden far greater than is necessary. It is through ignorance and carelessness that we create gardens that are needlessly needy.
On another front, most of the materials that go into the initial construction of the landscape -- the concrete, lumber, stone and gravel, and all the rest -- are either non-renewable or severely damaging to their environment of origin. Consider decomposed granite, a popular granular paving material that is attractive, inexpensive, easy to install and permeable to rainwater. On those counts it is a sustainable material. Yet, it is a soil type that is strip-mined from once-pristine mountains.
It is unfortunate that even proponents of sustainable landscaping have for the most part ignored these off-site impacts and satisfied themselves with creating gardens that, while they may be internally more sustainable than conventional ones, pillage nature in the course of their development and so are mere symbols of sustainability. Indeed, their hypocrisy does violence to the idea of sustainability.
So, what’s a better way? How does a sustainable garden actually work? Here are some of the nuts and bolts of this evolving approach to gardens...BUT WHAT DOES IT LOOK LIKE?
In the old xeriscape days, some people were afraid that the government was going to come and take out their lawn and replace it with cactus and rocks. Similarly, sometimes the idea of a sustainable garden conjures up the image of a barren, sad place that bears little relationship to the gardens we know and love. What will you have to give up to gain all these benefits? And what will it look like?
Well, the truth is that a sustainable garden can look pretty much like any other garden. Sustainability is independent of style. A Japanese garden can be sustainable. So can an English border, a desert garden, you name it. About the only thing you might have to forsake is that acre of bluegrass in the front yard, but even that could be more sustainable if it were replaced with a yarrow lawn that uses half the water and requires mowing only a few times a year.
Design your garden in whatever style you want, applying the principles of sustainability as you go.
THE GARDEN AS A SYSTEM. First and foremost, a sustainable garden is a system, just as nature is a system, just as the human body is a system, or for that matter a computer or an automobile or a toaster oven. It consists of a complex of interrelated parts that work together to create a functioning whole. Just as your body remains alive and healthy due to the combined and harmonious workings of the respiratory system, the circulatory system, the endocrine system and all the rest, so a well-designed garden will thrive when the insect system, the soil system, the water system, the plant system, the drainage system and many others are united in the common task of preserving the integrity of the whole. Until the garden is designed and managed as a system, our relationship to it will be primarily reactive -- pulling weeds here, cutting back overgrown plants there, watering when rainfall is insufficient for proper growth, fertilizing when the native soil cannot bear the demands for nutrition placed upon it by hungry exotic plants.
RELATIONSHIP TO PLACE. No system that is placed in an unfavorable environment will ever function successfully. Imagine a car in a world with no gasoline. For the garden to work well, it must have a finely-honed relationship to place. This means using plants from appropriate climates that will survive for the most part on what nature offers here and now, without subsidies from outside. The natural soil will be hospitable to these plants without the need for amendments and fertilizers. The natural rainfall will be adequate to meet their water needs. The temperatures will be agreeable to them without artificial modifications of the microclimate. In other words, the garden will be adapted to the carrying capacity of the land.
The hardscape elements -- patios, walkways and the like -- will be placed to take advantage of natural site features and microclimates and will be built of simple materials, preserved in a state of nature or nearly so, and that come from on site or nearby.
In the ancient days of Japanese gardens, the designer would spend a year on the site, watching the sun come up and go down again, every day for a complete cycle of seasons. In this way, he was able finally to understand the site well enough to make propitious decisions in creating the garden. Today, we expect drive-by design and we get the results we deserve.
HOMEOSTASIS. Nobody gardens nature. Have you ever wondered how that works? A natural ecosystem exists in a state of active balance, remaining stable until a triggering event changes the rules for a time. A hillside of 20 year-old chaparral is an example of what botanists call a "climax plant community." That is, one that has reached its mature state and will remain quiescent until it is disturbed, typically by wildfire. In the climax condition, natural processes go on at a languid pace -- weeds are shaded out by the dense canopy of Ceanothus and toyon and sage, animal burrows are undisturbed by land movement, plants gradually grow larger, insect populations remain stable. Biologists define "homeostasis" as "tending to maintain a relatively stable internal environment." By designing a garden in which the plants are given a favorable environment and room to grow, it is possible to create a homeostatic condition that will serve the garden and the gardener well for decades to come. In ignoring this principle. we create gardens that are sub-climax plant communities, always in a state of instability and therefore demanding of much care and many resources.
INPUTS AND OUTPUTS: A properly designed garden brings in fewer materials for its construction and later for its care, and generates little in the way of greenwaste, air pollution and other flows to the outside world. Let’s think for a moment about what comes and goes in the garden and how we might use less without giving up any of the things we want.
INPUTS: BUILDING MATERIALS: Consider first what is on the site that might be utilized to advantage. Boulders can be rearranged into an attractive retaining wall or dry streambed, for instance. Soil can be molded into adobe blocks and those can be used to build walls and other structures. Poles cut from that stand of weedy Eucalyptus trees can be used as lumber for arbors, fences and other garden woodwork. Similarly, whips pruned from fruit trees can be woven together into an attractive fence or trellis. The more you can use from on site, the less damage you do to other places, the less pollution is caused by trucking things in from far away, and the more money you save.
In many cases, materials of some kind will need to be brought in, especially where structures and paving are involved. Turn to re-used materials like railroad ties and broken concrete for your first choice. If they don’t satisfy, select from materials such as wood that come from renewable sources rather than things like concrete that, though abundant, is non-renewable. Also consider the "embodied energy" of the material: the total energy that is required to produce and deliver the material to you. Minimally-processed materials like lumber and decomposed granite and gravel have a low embodied energy, while things like brick, tile and concrete have a high embodied energy. Don’t forget recycled materials -- plastic lumber made from soda bottles and wood waste for example. There are even ways to treat ordinary soil so that it will solidify into a solid surface for walkways and roads. Finally, ask where things come from and consider the impact your purchase will have at the source.
INPUTS: WATER: Conserve water by selecting plants that are native to a climate similar to yours and that are known to be drought-tolerant. Then provide a high-efficiency irrigation system such as drip and learn to manage it properly, applying only enough water to replace what is used up. Mulch all your plantings to reduce evaporative losses from the soil, which can be significant. Keep weeds down; they use water too. Consider planting less densely to match the biomass to the carrying capacity of the land. And of course, reduce lawn areas to only that which you will use functionally, not ornamentally. Finally, where it is appropriate and safe to do so, grade the site (and perhaps build a dry streambed or percolation basins) to keep valuable rainwater on the site. You might even consider installing a cistern or other rainwater storage system to hold water for use during the dry season. It is possible to have a full, attractive planting with little or no supplemental watering during normal rainfall years. Remember, nobody waters nature.
INPUTS: FERTILIZERS: Minimize the importation of fertilizers by selecting plants that have low nutrient requirements and by fertilizing less often at lower application rates. The best fertilizer is compost that has been made from the very plants you’re fertilizing, plugging another leak to the outside world. If you do have a lawn, use a mulching mower that finely cuts the clippings and blows them back down into the lawn, possibly the world’s shortest trip to the compost pile. This is called "grasscycling" and it really works.
INPUTS: PESTICIDES: Similarly, reduce the need for pesticides by planting pest-resistant varieties and giving them satisfactory growing conditions. Just as a person thrives with a good diet and plenty of exercise and sickens in the absence of these things, so it is with plants.
When pests do show up, practice a little benign neglect first. Think of insects as co-inhabitants of the garden and remember that for most pests there will be one or more kinds of predators that can show up to keep the situation under control, at no cost to you. If a pest problem begins to get out of hand, import an appropriate ben-eficial insect as your first line of defense. Beneficials are efficient and voracious and never take a day off. Besides, learning about the relationships between insects is as much fun as learning about plants. Only if the beneficials don’t work (and please give them time to do their job) then you might consider using a least-toxic pesticide like insecticidal soap to knock down the population.
If a plant suffers from chronic, disfiguring pest damage, consider replacing it with a more appropriate species. Remember that of the hundreds of garden chemicals, only a handful have ever been tested for their effects on people, animals and the environment. Besides, volatilization of garden chemicals contributes to air quality problems.
There’s one other secret about avoiding pest problems and that is to build diversity into your plant palette. A mono-culture is much more vulnerable to pests and diseases than a more complex blend of things from many plant families.
INPUTS: HERBICIDES: Rather than applying herbicides, keep weeds down by avoiding large expanses of low-growing ground covers that provide newly-germinated weed seeds with a perfect environment for their development. Use a drip irrigation system to keep the soil dry and therefore unwelcoming to weeds. And mulch! Apply 3 to 4 inches of organic mulch such as shredded bark or tree chips in all planted areas. (Avoid letting mulch pile up around the trunks of plants, and watch out for tree chips that contain lots of live seeds or come from diseased trees.) Hand pull weeds when they’re young, remembering the old gardener’s adage, "One years’ seeds is nine years’ weeds."
INPUTS: FOSSIL FUELS: Fossil fuels are used in the garden in some sneaky ways. Of course, trucking materials from afar and making trips to the landfill burns gasoline, but do you realize that many chemical fertilizers and pesticides are made primarily from petroleum byproducts? And of course, all that gas-driven equipment uses petroleum, too. By planting right-sized plants that don’t need cutting back so often, and by keeping their growth steady with a lean diet of organic fertilizer and water, you’ll be reducing the need to use all that equipment to cut them back and haul them to the dump. (And don’t forget that the soft new growth stimulated by fertilizers and water and constant pruning makes the plants more susceptible to pest infestations.) If you do need to prune, use hand tools rather than power tools to eliminate one more source of fossil fuel use.
INPUTS: TIME: A sustainably designed and managed garden will require much less time to care for, because it is inherently stable. By taking our cues from nature, we adopt the self-maintaining character of the natural environment. A plant with room to grow is one that doesn’t need to be pruned. A healthy plant is one that doesn’t need to be sprayed. A building material that is at or close to a state of nature (such as a boulder) doesn’t need to be cared for like many highly-refined materials systems (painted wood, for instance). And build things to last so that you don’t have to replace or repair them for a long time.
INPUTS: MONEY: A garden that uses so few materials and requires so little care has just got to be less expensive, right? Right. Even if the design and installation were to cost more (which probably won’t be the case) the garden will still be much cheaper to live with because there’s not much to do but enjoy it. You’ll start getting a return right away and it will continue for the life of the garden. In fact, one of the best things about a sustainable garden is that it gets easier and easier to live with, because it grows more and more stable as it matures. Compare that with a traditional garden that demands more and more time and money as the trees and shrubs get too big and need to be cut back oftener and oftener, as the thirsty plants grow larger and need more water, and as the poorly-built structures need constant tinkering to keep them from falling apart. With a sustainable garden, you time and your money are yours to enjoy.
OUTPUTS: GREENWASTE: The biggest item on the output side of the ledger is the trimmings that leave your garden and go to the dump. Why have we accepted this for so long? By and large, the only reason for trips to the dump is that the plants don’t have enough room to grow. Why plant a 20 foot tall plant when you want a 6 foot hedge? Why plant a 100 foot tall tree in a small patio? And why, please tell me, put Juniperus tamariscifolia, which grows up to 20 feet in diameter (you could look this up) into a 5 foot wide parking strip? Yet these things are done all the time, and not just by naive amateurs either. Yes, you might have to wait an extra year for a right-sized plant to grow to the size you want, but you’ll be saving yourself a lifetime of cutting and hauling and looking like a fool.
So plant the right size plants and then allow them to grow naturally, pruning only to remove crossing or damaged branches. By fertilizing and watering less, you also generate less greenwaste. Then, recognize that greenwaste isn’t really waste at all, but a valuable element in the garden system -- feedstock for your composting operation. Chop it into small pieces, pile it up (half green stuff and half brown stuff), squirt some water on it and you’re on your way to a supply of compost that can be returned to the garden to supply valuable nutrients and beneficial soil microorganisms. Throwing away garden trimmings is like burning dollar bills.
OUTPUTS: POLLUTED RUNOFF: Fertilizers and pesticides leach out of the soil with each irrigation and find their way into the groundwater, streams and the ocean. If you don’t use them in the first place, you won’t have to worry about this problem. And if you grade the site to retain water, any bad stuff you do have around will stay around.
OUTPUTS: AIR POLLUTION: Similarly, the volatilization of fertilizers, herbicides and pesticides into the atmosphere won’t be a concern if you don’t introduce them into the garden in the first place.
According to the New York Times, a lawnmower operated for an hour emits as much pollution as driving a car 50 miles. Far worse, in two hours, a chain saw emits as many hydrocarbons as a new car driven 3,000 miles! That’s not a typo. When the California Air Resources Board added up the pollution from all the power equipment used by the landscape industry, loggers and arborists, it equaled that produced by 3.5 million cars driven 16,000 miles each. That doesn’t even count equipment used by homeowners. Reduce this problem by cutting way back on your use of gas-driven garden equipment, especially two-cycle engines that power chainsaws, weed whackers, blowers and hedge trimmers. Use hand tools or electric tools instead. And remember that because your garden is designed to require little pruning, you’ll be needing this equipment less anyway.
HARVESTING FROM THE WASTE STREAM: We can go beyond merely minimizing our consumption and waste. The garden can actually reduce overall waste by harvesting materials from the waste stream. Here are a few suggestions; with a little imagination you can come up with more. Glean feedstock for your compost pile from restaurants and grocery stores. Try coffee grounds and discarded produce, for instance. Use chips from tree trimming operations in the neighborhood to mulch your beds; tree companies are usually happy to drop off chips for free or for a modest fee. Better yet, use the wood as lumber for garden projects such as benches, fences, etc. Broken concrete can be stained with ferrous sulfate fertilizer to look like stone and then stacked to make retaining walls or set in a bed of sand to make stepping stones or a patio. Waste of many kinds from construction projects can be turned into small structures or garden art. One of the nicest planters I’ve ever seen was a discarded brake drum from a large truck; these can be obtained for very little money from a heavy-equipment mechanic or a junkyard. There’s a mountain of interesting material going right by your house every day on its way to the landfill. Use your imagination and make use of some of it.
PROBLEMS NO ONE HAS SOLVED YET: Until they learn to make pipe out of soybeans (not so wild an idea as you might think), we’re stuck with PVC pipe and all its drawbacks. For now, use drip tubing where you can; it’s made from non-reactive polyethylene that doesn’t contain dioxins and doesn’t require solvents for assembly.
Many recycled mulches are made from construction waste that may contain lead and other contaminants, or from chipped trees that may inoculate your soil with oak root fungus and other diseases. Plus, some of these materials can be very flammable, especially during hot weather. For now, I recommend using caution when purchasing these materials and if there is any doubt, use shredded redwood or fir bark instead.
As far as I know, no one has come up with a durable, hard paving material that’s also sustainable. For now, we’re stuck with concrete. In fact, paving materials in general tend to be destructive at their source. Use mulches in pathways where there is minimal traffic and save the hard stuff for the front walk and other public areas. If you must use concrete, specify a high-flyash content mix that uses waste from coal-burning power plants, and is much stronger and more durable than conventional concrete.
GO BEYOND SUSTAINABILITY: Unlike buildings, gardens are naturally solar-powered. They are also capable of producing food for people. Plant an orchard and a vegetable garden. Make use of the productivity of your land to grow food instead of just flowers. It’s sure to be superior in every respect to those supermarket tomatoes that we all like to belittle. If you produce more than you can eat or preserve, give the rest away to a homeless shelter or rescue mission. Or to the neighbors; they like ripe tomatoes and juicy plums, too.
Don’t forget the wildlife. Provide shelter, nesting materials and food for birds, mammals and other critters. Grow plants that attract beneficial insects and they will reward you by patrolling the garden for you.