When designing your backyard naturescape project, it's important to consider the ecological impact of your landscape materials. Some woods are treated with toxic chemicals to prevent breakdown, and many prefabricated landscape materials have complicated carbon footprints. In her book The Naturescaping Workbook: A Step-By-Step Guide for Bringing Nature to Your Backyard, (Timber Press, 2011) Beth O’Donnell Young offers information on the sustainability of traditional landscaping materials while sharing eco-friendly alternatives.
Think Before You Buy
To be conscientious about landscape materials, first you must be conscious. Question everything about traditional landscape materials, the things that you can purchase at your garden center, your local big-box store’s gardening department, your lumberyard, even your stoneyard. Because, as with a lot of current landscape practices, the status quo is damaging our earth.
What follows are the things to think about before you buy something new. These are guidelines, not scriptures; thought provokers, not hard-and-fast rules. Your best bet is to consider the full range of options, throw out what doesn’t work for you, and weigh the rest. Making conscious choices—rather than buying what the commercials tell us to buy—is the best we can do.
To Purchase or Not to Purchase
Do you really need to buy it? Or can you beg, borrow, or share it? Perhaps you could rethink purchasing that fancy play structure—after all, all the kids in the neighborhood need only one. Maybe you could have the trampoline in your yard and someone else could have the swing set. Does every home need a patio set big enough for parties? What if all the neighbors chipped in for an extra patio set that anyone could borrow? Rethinking our natural tendency as Americans to be independent might lead to some good neighborly relations (or at least you might meet the neighbors).
If you decide you need it, you can still stretch your thinking process to go beyond the standard materials. Think back to the time when folks could not go out and buy prefabricated landscape materials and install them in a weekend, yet still wanted walls and fences, an overhead structure, a nice place to sit, even pools and fountains. What did they do?
They used what was at hand. Boards, yes, but also branches, grasses, bamboo canes, straw, dried manure, crushed rock, chalk dust, hide, hair, and hay. Twigs were soaked to make them pliable and then bent and tied or glued into trellises, arbors, and furniture. Thin branches were woven between stakes to make fences or daubed with gypsum to make durable walls. Bamboo canes were used for fences as well as paving and ornamentation. Mud and straw were combined to make bricks and roof tiles. Stains were created from berries and vegetable extracts. Structures were weatherproofed with gypsum, mud, and/or straw. Stone was broken and carried to make paving, walls, and water features that stand centuries after being built.
To find out what techniques were used in your region, you may have to do some sleuthing. Your local historical museum would be a good place to start; it may have information on how local people lived before industrialization, what materials were abundant, and how they were used. Another source of ideas is to look toward ancient (or just preindustrial) cultures with similar climates to yours: if you live in the coastal Northeast, you could borrow ideas from England and Japan; in the arid West, you could look toward the Middle East and North Africa, and so on. Researching the old ways of making paths, fences, walls, and overhead structures around the world might inspire you to start an entirely “new” way of hardscaping in your area—one that is gentle on the land as well as your wallet.
By-Products, Not Products to Buy
Thinking in terms of using materials at hand, particularly free materials that are the by-product of some form of local production, can save you a lot of money. Ask around. Find out what the local farms grow and what their by-products are. Here in Oregon we have hazelnut groves, and the cracked shells make a lovely path material that is long-lasting and that ties in visually with nearby trunks and branches; walking on this material generates a sharp crunch that is somehow restful. Similarly, Mount Vernon was lined with genteel white paths, a by-product of the Potomac River’s oyster industry (in George Washington’s time there were no restrictions on removing oyster shells). Farms are usually eager to give you by-products that are useless (or overwhelming) to them, but you will have to haul these gifts away yourself. With a borrowed truck and a batch of homemade cookies (for the farmers), you’d be surprised what you might glean—anything from aged manure to mint hay to used tools.
Don’t forget local manufacturers. Asking friends what their company’s (or department’s) waste products are might get you thinking: maybe I can make a fence of that, or stack it into a wall, or lash it together to make a trellis. Shipping pallets, for instance, can easily be recycled into compost bins. Stone scrap left over from the manufacture of kitchen counters can be turned rough side up to serve as stepping-stones.
Another source of materials is our public lands. If you ask the appropriate local authority for permission, you might be surprised to find that you can help yourself to (a small amount of) an abundant natural resource, such as beach sand, river gravel or cobble, or fall leaves. Before asking for permission, be sure to have in mind what you want, how much you want, when you would like to remove it, and how you propose to haul it.
Reimagine and Repurpose
Every culture since the dawn of time has used what is abundant to make shelter and landscape structures. Our twenty-first-century world also has some things in abundance. Sadly, our abundance can be found in our landfills, where we have discarded household goods that have outlived their usefulness or stylishness, or simply don’t work anymore. Enter repurposing. Repurposing takes a usually discarded item, say an old door, and fixes it up so it can have a new life as something else, say a picnic table. It is seeing the potential. It’s cleaning something up, sanding it, turning it upside down, cutting it up, epoxying it, attaching it to something else. It’s painting it chocolate brown, lime green, or sparkly gold. It’s giving old things new life.
I’ve seen great repurposed items in gardens: an old desk fitted with a secondhand sink to make a handy potting bench with a built-in soil funnel; cut-off sneaker soles placed in a concrete path to look like footsteps; and even a string-and-yogurt-cup rain chain. This has no bounds! House salvage shops and secondhand stores are great places to start. Walk around these places with new eyes; don’t see what it was but what it could be. And, above all, have fun with it.
One caveat, though: to avoid tackiness, the repurposed part should not be easily identifiable as its former self. The less it looks like its past life, the better. No old shoes planted with succulents, no brass bed filled with pansies—these have already been done. Better to make beautiful, useful garden pieces and elements that look vaguely familiar but can’t quite be placed, like a movie title that is maddeningly on the tip of one’s tongue. It will add a touch of intrigue to your yard, and humor as your visitors solve the riddle.
If You Must Buy New . . .
In some cases, buying new is your only alternative. Purchasing new can be guilt-free if you choose products that are nontoxic, have high recycled content, are locally produced, are durable, and are modular. It would be difficult to find one product with all of these attributes, but thinking in these terms will help you make informed decisions.
Toxic substances to avoid include paints and coatings with volatile organic compounds or VOCs, which contribute to smog and groundwater pollution. Also avoid arsenic and creosote, often used as wood preservatives in the past and found in old railroad ties, which have been sold as landscape timbers for many years. Stay away from any treated wood, and perhaps even rethink wood if it decays quickly where you live.
More and more new products have high recycled content. If you buy them, you will grease the recycling machine. Recycled content is high in some plastic landscape items such as rain barrels, composters, hoses, composite decking, and furniture. There is even recycled wood mulch, made from old pallets rather than virgin wood. If you don’t see any of these products around, ask your retailer or write a letter to your local paper. Be the grease!
Taking a cue from locavores, who make a good effort to eat only locally grown food, you can make a good effort to purchase only locally manufactured landscape materials. You might find, as the locavores do, that this is harder than it sounds. But it can be done with a bit of sleuthing. Start at your garden center—ask where the item was made. If they can tell you it was made nearby, it’s okay. If they don’t know, ask for the name of the distributor, who can tell you where it was manufactured. You may find that the product is not made nearby at all, but by asking around you are raising retailers’ awareness that this is important to consumers.
When given a choice, choose durable. For example, if you have decided on plastic lawn edging (to keep the grass roots from spreading to the adjacent flower beds), choose the more durable plastic. But also consider the bigger picture: what else can keep the roots at bay? Perhaps the answer is deep-set concrete blocks or natural stone.
And last, when buying new, chose modular over built-in. For example, if you want a patio, consider setting concrete blocks or natural stone in tamped sand rather than poured concrete (but do it accurately so it lasts for years without becoming uneven). That way, as the tides of landscape fashion change (they do, but slowly) you can give away, resell, or reset the pieces as you please—with no waste generated in the process.
Regardless of whether your landscape materials are shared, natural, by-products, repurposed, or new, there’s one last (and lasting) thing to think about: what happens when they are no longer needed? Will they take a lot of energy to break up and remove? Will they fall apart, leaving an unsightly, even toxic, mess?
The best choice, in respect to the afterlife, are the biodegradable items. Nature knows what it is doing. Natural materials do not need to be removed; when they are done, they revert to their elements and regroup into something cool like food for a termite or mealybug. And rather than requiring energy to break down, they generate energy for the garden as they all but magically disappear. Espaliered trees, walkable ground cover, even cacti can make excellent hardscape stand-ins; we just need to expand our definition of hardscape.
Another good choice in terms of its afterlife is a hardscape material that can be donated or sold to others when you are finished with it. If you are not sure if people will want it, you can peruse home salvage shops, want ads, or want-ad websites such as Freecycle or Craigslist to see what people give away or sell.
Know the Facts About Popular Materials
Some of our favorite landscape materials and features contribute to environmental degradation in ways most people are not aware of. For example, did you know that the piping commonly used in suburban irrigation systems is extremely toxic in its manufacture? Becoming aware of these damaging practices and of alternatives to popular materials will help you to decide which materials are right—or not right—for your naturescape.
Concrete traditionally has three main components: Portland cement, aggregates (small rocks), and sand. Portland cement is a product of firing clay and limestone to 2700 degrees Fahrenheit. Besides requiring this staggering energy input, producing the cement releases lead, arsenic, and mercury into the air—and huge quantities of carbon dioxide. For every ton of cement produced, approximately one ton of carbon dioxide is released. Worldwide cement production accounts for 5 percent of global emissions of carbon dioxide, the main cause of global warming.
On the other hand, because concrete’s heaviest component, water, is added onsite, transporting concrete produces less carbon dioxide from fossil fuels than do natural stone or concrete pavers. Also, concrete recaptures some carbon dioxide as it ages. And from a designer’s standpoint, there are reasons to love poured concrete. It is extremely durable and can be a highly creative medium. It can be formed to any shape and it comes in lovely colors that can complement the landscape (terra-cotta and near-black are my favorites). Interesting tiles, stones, or whatever (refrigerator alphabet letters?) can be added after the pour. The surface can be stenciled or stamped to bring a large expanse down to human scale.
For an earth-friendly variation on poured concrete, request a concrete mix with up to 50 percent fly ash (a by-product of coal production) instead of 100 percent Portland cement. Request that the aggregates be from crushed concrete rather than mined rock.
Good alternatives to poured concrete include tamped earth, tamped gravel, and decomposed granite, depending on where you live. Natural stone is always beautiful. Broken-up concrete reset in gravel (upside down or not) makes an interesting surface. Concrete driveways can be revitalized—and made permeable—by breaking up the concrete and re-laying it this way, too.
Precast concrete pavers and wall blocks
Portland cement, a greenhouse gas contributor, is a key ingredient in concrete pavers and wall blocks. In addition, greenhouse gases are released in the transport of these heavy blocks. On the other hand, pavers laid over gravel can make a nice permeable driveway, parking area, or patio—and permeable paving doesn’t harm your creeks and rivers and underground water. So should you use concrete pavers and blocks?
According to the Mid-Atlantic Precast Association, precast concrete can be made in a more earth-friendly fashion with industrial by-products such as fly ash and slag. Ask if your store’s precast pavers or walls blocks are made with these recycled materials; if you don’t find any, it wouldn’t hurt to request them. If enough of us do that, we will eventually see change.
Instead of precast concrete pavers, you could consider the alternatives to poured concrete listed earlier. For concrete wall blocks, there are quite a few alternatives. You could use natural, local stone, either dry laid or mortared in place. Walls like this have lasted for centuries. Locally produced brick might be a viable option—affordable as well as sustainable—depending on where you live. The same goes for reused brick.
Hempcrete is a new material made primarily from hemp stalks and lime. It resembles concrete blocks but does not have the compressive strength of concrete. Its greatest asset is that it is carbon-negative; that is, the hemp production absorbs carbon dioxide, and even the bricks do, albeit very slowly. It might be something to consider if it is produced locally. There are also concrete-block alternatives such as large honeycombed blocks of clay, or compressed earth, but again, it only makes sense to use these materials if they are produced locally.
I would not recommend lumber as an alternative to wall blocks, however. To keep the wood from rotting, potentially toxic chemicals must be used to treat the wood and a waterproof membrane must be placed between the wall and the soil. Also, these walls are not extremely durable and need to be replaced in twenty or thirty years, which uses up more materials. And if the wood was soaked in preservatives, it is not suitable for many other uses and therefore most likely cannot be recycled or reused.
Bricks are a popular choice for garden paths and walls because they are sized to be easy to work with, they are durable and strong, and they can be made locally around the globe. But firing the bricks in kilns requires huge amounts of energy, as does transporting them if they are not locally produced. And bricks need mortar to adhere them together in a wall, so this means using cement unless lime mortar is used.
The most sustainable choice is to use reclaimed bricks that are sourced locally. For patios and terraces, they can be set in a base of sand at least an inch deep to keep weeds from growing in the joints. Or you can set the bricks directly in the soil and add tiny succulents, herbs, or mosses in the gaps to keep out weeds.
For walls, you can mortar the bricks over a concrete base (there’s no way of getting around this) using lime mortar rather than stucco. Lime mortar is simply water, sharp sand, and hydrated lime and contains no cement (stucco does). Using lime mortar will allow the bricks to be reused again in the future. Lime mortars are not as strong or durable as stucco mortars, however, so you might want to check with a local mason to find a lime mortar mix that will hold up in your climate.
Make sure if you use reclaimed brick that the brick has been fired especially for outdoor use and isn’t from interior house walls. The latter isn’t as hard and will start to flake and chip; a hard frost will turn indoor-type brick to dust.
Asphalt—also known as blacktop, tarmac, or AC (for asphaltic concrete although there is no concrete in it)—is not exactly a green product, but neither is it the worst choice. It is 100-percent recyclable and can even be removed and re-layed completely on-site. This is usually done with larger pavement projects; for driveways, the old asphalt is normally broken up and trucked away for recycling, and new asphalt—sometimes made with recycled content—is brought in.
Asphalt is made of crushed gravel and sand bound together with a by-product of crude oil refinement. It must be laid hot, and of course big trucks are needed to carry the raw materials to the site and also extrude the asphalt. A newer kind of asphalt, called warm-mix asphalt, requires less heat when it is laid and is considered a greener alternative. The product is just as durable and strong as the hot-mix asphalt. For a short driveway that gets very little traffic, you may even consider the cold-mix alternative, which is usually recommended for service roads because it is not as durable as the other types.
The jury’s out on whether using asphalt as a driveway (and/or path) material is good or bad for the environment. On one hand, it uses fossel fuels in its raw materials, transportation, and production. On the other hand, it is recyclable; a homeowner can choose the energy-saving warm-mix asphalt (or even the cold-mix); it is available in a permeable form, which is good for our water sources; and it can be made in light tones so as not to contribute to the urban heat island effect of many of our cities and suburbs.
Wood wants to decay in the out-of-doors—that’s a given. There are some woods that decay more slowly than others, but those are expensive and from faraway places. Often, homeowners choose inexpensive, less-resistant wood that has been treated with preservatives to resist decay. The problem is, these preservatives are sometimes harmful to humans (arsenic was a common ingredient in wood preservatives until December 2003) and can be tracked indoors, where they contribute to indoor pollution. Decks often need reapplications of stain and varnish to look good and avoid splintering.
Imported woods with incredible strength such as ipe (Brazilian walnut, pronounced ee-pay), mahogany, and teak are sometimes used for decks. They are often touted as sustainable because they are highly decay-resistant, but transportation and tropical forest degradation may put that sustainability equation a little out of balance.
For an earth-friendly variation, choose a decay-resistant wood that is grown locally and sustainably. Resistant woods that are endemic to your region are your best bet. In the United States, look for redwood, black walnut, cedar, black locust, eastern red cedar, juniper, and cypress. Leave the wood untreated, or use earth-friendly stains and sealers. Excavate soil and place boulders or old concrete under the deck where it would otherwise come in contact with soil. If you can justify using ipe, mahogany, or teak, use wood certified by the Forest Stewardship Council.
As an alternative to wood, a combination of wood and plastic called composite can be used for decking, fencing, and retaining walls. You might like the idea that it is a product of recycled plastic and that no stains or preservatives are needed to keep it looking good, but some manufacturers allow shredded PVC in the product. PVC is not recyclable in most places so you may end up with no choice but to dump your old decking into the landfill. Instead, buy PVC-free composite decking and make sure it is recyclable where you live.
Decking tiles are a relatively new alternative to traditional wood decking. The tiles, which measure about a foot square and are made from cut natural stone or composite, are placed over a metal grid.
This excerpt has been reprinted with permission from The Naturescaping Workbook: A Step-By-Step Guide for Bringing Nature to Your Backyard by Beth O'Donnell Young, published by Timber Press, 2011.