Backyard Reforestation:  A New Approach to Landscaping the Washington, D.C. Area
 

Within the confines of an urban or suburban yard, no matter how tiny, lies enormous landscaping potential.  Whether you're starting out with a bare yard, or creating order from overgrowth, every yard holds the potential for creativity.  Even small, cluttered lots can be delivered to extraordinary beauty and individuality.  Several thousand eligible plants exist in commerce, and hundreds more are introduced every year.  Often, these new introductions include more appropriate varieties of old favorites previously excluded due to the main restrictions on in-town plantings:  ultimate size, pest and disease problems, and/or intolerance to air pollution. Traditionally, urban and suburban yards have been divided into play space for children and living areas for adults - lawn, decks, and patios.  The dream of owning a home carries with it visions of children romping on an expanse of green grass, and barbecues on the deck or patio - images of well earned relaxation.  Today, however, work weeks are getting longer, commuting steals more free time, and the dream is becoming a nightmare.  For many homeowners, the yard that beckoned as an oasis is now just another chore - and another impediment to leisure. Even when all of the weeding, mowing, pruning, raking, and fertilizing is finished, homeowners find that the time required to maintain a traditional lawn isn't the only source of stress in the yard today.  Peace and quiet are nearly extinct, overcome by noise pollution generated by lawn mowers, leaf blowers, and other motorized yard gadgets.  Environmentalists berate homeowners for using pesticides and fertilizers, citing the vulnerability of our watersheds.  Periods of "extreme" drought have become the norm during summer.  As our regional population grows, and open space gives way to development, water use on lawns is often restricted and sometimes completely unavailable. Another consequence of our modern lifestyle is the erosion of privacy.  We work in tiny cubicles, and drive smaller cars on crowded freeways.  Yards are smaller, and buffer zones a disappearing luxury.  Even on vacation, the quest for seclusion is often in vain. And finally, as forests are clear-cut and wildlife habitat shrinks, our air quality diminishes, and more species become endangered each year.  Controlling growth is an election year battle cry, but population gains and shifts cannot be legislated.  Development will continue as long as it is profitable.  A push is on to hold developers accountable for environmental impact, but it is the property owner who ultimately pays.  As voters and taxpayers, we can continue to demand that development take place in a responsible fashion, but as homeowners, we can do one thing more: take up the slack by creating forested habitat, composed primarily of native plants, in our own backyards. A forested garden is naturally conducive to relaxation and contemplation.  Strategic planting can reduce traffic noise and invite a thriving community of songbirds to lessen it that much more.  A multi-tiered planting can create absolute privacy, while actually contributing a feeling of expansiveness to a small space. Most people would agree that a wooded garden can be beautiful and inviting; but what is less apparent is how practical it can be.  What follows is a discussion of the roles played by the traditional urban yard, and how they can be adapted to the woodland with delightful results. The Outdoor Room A city garden is, first and foremost, a living area.  Unless you are fortunate enough to own an urban acre, leisure and recreation must be given some priority over creative expression.  Moreover, a look-but-don't-touch approach in a small space may not bring a good return if you should ever sell your property.  Too often we see a homeowner's lovingly planned, meticulously maintained showpiece dispassionately ripped out by successors. A well designed garden space - one that offers comfortable seating, scenic and seasonal variety, and a sense of connection to nature - is the more realistic goal of most homeowners.  Although open space is receding alarmingly, it is still possible to reach scenes of natural splendor by taking a two-hour car trip.  No one will succeed in recreating the Grand Canyon on a backyard scale, although attempts may provide a sense of whimsy.  What you can recover, even in the smallest garden, is some degree of solitude - a commodity that is now threatened even in backcountry areas. The Play Space The recreational needs of children and pets may be different from what you imagine. Maintaining an expanse of grass for children's play space is a thankless chore, and, unless you have room for a ball field, there's no real added value to a child.  Children (and dogs) will run blissfully around trees with an agility that's a marvel to watch.  A game of catch, or Frisbee, can take place in a shady avenue as small as, say, thirty feet by fifteen, and the groundskeeper doesn't have to worry about damage to the grass.  If you want to provide a soft surface to reduce the risk of injury, a thick blanket of playground mulch will improve your soil and protect your plants against drought, and it requires no maintenance except replacement every few years.  In many jurisdictions, mulch is available free for the hauling.  Some towns and counties will even deliver it to your dooryard. If you must have a green, living groundcover, there are several options that are more tolerant to drought and shade than lawn grass.  Many are just as tolerant of foot traffic, and they don't require mowing. Most children will be delighted to play in a wooded garden - how those trees can inspire a young imagination!  Add a special corner with a playhouse, tree fort, swing set, or sandbox, and get your kids directly involved in the planting process.  Eventually, they may even stop saying "It's too hot to play outside" in the summer.  No one will miss the lawn - least of all you. The Plantings Choosing a diverse array of plants, and placing them according to their needs, are the essential steps to a healthy, sustainable landscape, whether you are installing three plants or three thousand.  If you make this your rule as a gardener, you'll be doing your part to slow the spread of diseases and pests throughout your community.  (Try it with your vegetable garden as well.  Scatter your plants throughout your yard among your ornamentals; you'll be amazed at your yields.) For now, we'll dispense with more specific classification, and consider garden plants by dividing them into three unscientific categories: trees and shrubs, groundcovers, and perennials. When selecting plants, however, don't assume that a small space will be occupied by a perennial, or reserve all of your choice specimen locations for trees.  Dwarf shrubs make lovely, low-maintenance groundcovers, and large architectural plants - those with large, dramatic foliage and bold, distinctive habits - are usually perennials.  Of course, they stand out as specimens, but they add texture and structure to the landscape as background plants.  They facilitate the transition between tree and shrub, or shrub and groundcover, and are useful in breaking up a flat landscape.  Architectural plants also excel as foundation plants, effectively bridging the gap between natural scenery and structures. The Native Plant Dilemma In the past, the nursery and landscaping industries believed that the safest bet for planting a durable garden was to select proven natives for the cornerstones.  American beeches and elms were often the starting points for America's landmark gardens.  Unfortunately, horticulturists are scrambling to find and plant suitable replacements as these majestic natives fall prey to diseases, air pollution, and the pests that are the inevitable consequence of overplanting of a particular species. One reason for this devastation, the industry is learning, is the high-maintenance, disease-fostering practice of monoculture - i.e., planting rows and rows of identical or closely related plants.  Imagine what a shame it would be for your entire privacy hedge to be destroyed in one season by insects or blight.  Yet American municipalities routinely plant tens or hundreds - or thousands - of one type of tree along streets and walkways, and then return, frequently within ten years, to replace them as they succumb to disease, pollution, or the stress of having their roots trampled or paved. Today the focus in the mainstream nursery and landscape industries has shifted to varieties that are more quickly established in urban and suburban gardens. Many commercially available plants are hybrids and cultivars bred from the old native favorites, but increasingly, new introductions originate from Asia.  For a low maintenance residential landscape, some of these plants are superb performers.  We have used carefully-selected exotics in the past ourselves. However, many exotic plants that are well-behaved in their homelands are weedy and invasive here, sometimes choking out natives and harboring diseases and pests against which indigenous plants have no resistance.  Why nurseries continue to recommend these plants, let alone carry them, is a mystery to us, especially given the vast array of beautiful and virtually trouble-free native plants.  The value of using native plants - even in the smallest garden  (we're talking apartment balcony here) cannot be overstated.  And using them in more vulnerable ecologies, e.g., residential landscapes that border parks, preserves, forests, sanctuaries, and wilderness areas, is essential.  Any non-native plant that is inclined to reproduce itself freely, creep, or broadcast its seed via wind, water, birds or other wildlife, or even human activity should be left out of these areas.  This includes even plants native to other areas of the United States that may hybridize freely with indigenous plants.  The resulting offspring may be of no use to the wildlife that has come to depend on the plant over generations. Even the best behaved exotics - those that must be coaxed to reproduce - should not be planted near property lines in sensitive areas.  And there's no need.  Native plants include low-maintenance choices, evergreen shrubs and other screen plants, specimens suitable for cutting and formal gardens, outstanding fragrance plants, startling architectural foliage plants, and even slow, stately treasures such as orchids.  All have their roles, and all contribute something special to the local ecology. The true secret to vitality and longevity in our native species lies in preserving diversity - in the selection of species, availability of breeding stock, and in plant behavior and habit.  Ideally, natives are produced from open-pollinated seed from plants growing in the immediate area.  Unfortunately, in the Washington area, many natives are disappearing too quickly to justify the removal of seeds from fragile ecologies.  Some native plant advocates recommend selecting seed and stock from within a sixty-mile radius of the intended site.  This is excellent guidance for conservation and reclamation projects that is not yet practical for the urban gardener.  How can fifteen or twenty small nurseries supply one million households?  Vegetative propagation of plants selected due to their suitability for a particular ecology remains the most effective means of distributing large numbers of rare plants to large metropolitan areas.  As more sources for native plant material are established, we challenge landscapers and retail garden centers to make quality seed-grown stock of indigenous ecotypes the mainstay of their inventory.  That's what we're trying to do. In the meantime, some cultivars may fill the void.  To choose cultivars that can be integrated into a viable habitat, a homeowner may want to ponder the following: Many cultivars are sterile and provide no food value because they produce no seed.  On the other hand, sterile cultivars do not flood the region with thousands of seeds containing a single genetic makeup, as fertile cultivars can.  If sterile cultivars are allowed to spread off a private property, they may become as much of a nuisance as invasive exotics. Fertile cultivars are better than nothing when a rare and important plant is approaching extinction, but only if they were selected from naturally occurring plants (rather than made by humans through hybridization with non-natives, genetic engineering, or generations of garden breeding), and if they have essentially the same characteristics, particularly bloom time, as the diminished population they are replacing. If you are fortunate enough to locate a reputable grower of seed-grown, genetically diverse native species in your area, establish a relationship with the company.  Ask for recommendations to replace exotics.  If you purchase by mail order, remember the following: Purveyors of plants that have been dug from the wild, (or dug from private property in sufficient quantities to threaten the stability of the population) should not be rewarded with your business.  Always purchase only nursery-propagated (not just nursery grown) plants.  Recognize that out-of-control digging on private property consitutes "nursery propagation" by some standards.  Be suspicious of very low prices for very rare or endangered plants. Try to purchase plants grown from seed stock from your immediate area (e.g., piedmont or coastal plain), and your watershed (e.g., Chesapeake Bay) if possible.  They are used to local conditions and much more likely to thrive.  They will also bloom when local wildlife expect them to.  For example, hummingbirds depend on particular plants to bloom during their spring and fall migrations. Trees and Shrubs There is no scientific distinction between trees and shrubs.  Both are woody plants that retain the growth of previous years.  Of course, a tree is generally considered larger than a shrub.  Also, the term "tree" is generally used to denote a woody plant grown with a single leader, while a shrub is more likely to be multi-stemmed.  That said, it is often possible to obtain either habit in a desired plant.  A suitable "shrub" can be trained to a single stem, and a "tree" can be encouraged to sucker (i.e., send out shoots) to create a multi-trunked specimen.  However, it's best to select plants that exhibit the desired habit naturally. Trees and large shrubs are the backbone of a garden.  While it can be fun, and rewarding, to experiment with plants of borderline hardiness, exotic provenance, and incompatible culture requirements, to do so with your largest plants is an invitation to trouble. The ubiquitous white pine may be the signature evergreen of eastern North America.  Regrettably, it seldom thrives except in the interior.  Its widespread use for highway planting has proven a dismal failure due to its sensitivity to salt and air pollution.  Leave it out of your yard; there are many beautiful conifers that thrive in urban conditions.  Don't make the mistake of thinking you're immune if you live in a pastoral suburban setting.  Congestion and smog are encroaching, and there's no place for them to recede.  Some trees not only tolerate air pollution; they help eliminate it. The Bradford pear (Pyrus calleryana) is, perhaps, the most widely planted tree in the east.  What a shame!  They are horribly invasive exotics.  They are also so prone to breakage that many mature specimens are missing large chunks.  Why, then, are they the first pick to line the streets by the hundreds?  The native fringe tree (Chionanthus virginicus) is a worthy substitute, with a beautiful spring show of white fringe-like flowers, a small size that makes is suitable for planting under utility lines, and the drought and pollution tolerance necessary for a street tree to succeed. A word about spacing:  Too often we see trees and shrubs that are crooked, stubby, or sparsely branched because the plants were spaced too close together.  Respect the advice of experts who caution against spacing for immediate gratification.  Remember that plants that are pruned yearly will never look natural.  However, if you can obtain small, inexpensive specimens, and recognize that you will eventually have to remove some plants, crowding woody plants is a viable alternative to a lawn.  After all, this is how nature reclaims stripped land.  Plant young saplings and surround them with native grasses and sun-loving perennials.  You don't need to pay top dollar for perfect specimens.  Trees that are slightly irregular (but still healthy) will look more natural.  As they grow, your meadow will gradually give way to a forest that will nurture more delicate woodland plants.  You can thin the forest by harvesting young hardwood trees to use as kindling or smoke flavoring for barbecuing.  Cut them while they are still young - around fifteen to twenty-five feet tall, or when the trunk is three or four inches in diameter when measured six inches above the ground.  This could take anywhere from five to fifteen years, depending on the tree's growth rate and growing conditions.  At this size, they will be small enough for one or two people to fell safely with a hand saw.  If the temporary trees are selected for ease of transplanting, and placed near plants that tolerate root disturbance, they can be relocated or given away. Perennials and Groundcovers Perennials, by their nature, are more resilient than trees and less likely to be threatened by disease and pests.  However, many treasured natives are threatened with extinction simply due to loss of habitat.  Responsible nurseries are collecting seed and recovering plants from wild areas before they are lost to development.  By including them in your landscape, you can help ensure their long-term survival. Lawn grasses (perennial rye, zoysia, bluegrass, and fescue) are the quintessential all-American groundcover.  English settlers brought their passion for lawns over with the first expeditionary forces.  It's easy to understand why grass is the  groundcover of choice in England, with its cool, wet summers.  There is no more beautiful backdrop for a prize specimen plant than a lush, green, freshly mown lawn. However, in America's mid-Atlantic region, a lawn retains its freshly mowed appearance for about forty-eight hours.  The lush green effect of May gives way to a parched, distressed appearance around mid-June, without a time-consuming, environmentally detrimental regimen of watering and applying weed killers and fertilizers.  Scorching heat and drought, weeds, pests, incompatible soil - we have all of the ingredients to sabotage lawn grass, yet it's the only plant in many yards - often because most of us are aware that grass doesn't grow well under trees!  Most homeowners even go to great lengths to deprive their lawns of nature's own fertilizer - leaves!  Using a mulching mower to shred fallen leaves (instead of raking them) distributes nutrients to the groundcover and replenishes topsoil.  It also prevents blisters on your hands and reduces the fire hazard that is created by piles of dry leaves.  Left intact on the woodland floor, autumn leaves provide an added maintenance benefit; they discourage the germination of weeds in spring and summer.  It's a good idea, however, to clear the leaves of your shrubs and more fragile perennials. Bring It All Together With Hardscape and Accents "Hardscape" is an industry word for any installation comprised of durable goods, e.g., decks, wooden bridges and walkways, concrete, pavers, and stone walls.  They can be used to transform difficult areas into living space, create privacy or enhance views, or make a yard more accessible for people who have more difficulty getting around. Responsibly harvested rot-resistant woods and engineered products combining wood and recycled plastics are replacing pressure-treated lumber, the region's standby for outdoor living space through the seventies, eighties, and nineties.  Decks built from naturally rot-resistant materials continue to be an excellent choice because they are created from renewable materials, and they do not drastically alter the natural process of groundwater percolation. Many municipalities have restrictions on the percentage of a lot than can be excavated, paved, or improved with permanent structures.  This reflects a recent (and very necessary) policy shift toward limiting the runoff of stormwater, which carries fertilizer, pesticides, pesticides and other pollutants into wetlands and waterways in proportions  that are creating enormous dead zones.  Remember that performing any significant re-grading on your property without consulting a licensed civil engineer or landscape architect is never a good idea. Patios and terraces of stone and tile can be part of a responsibly designed landscape if they are substantially dry-laid, over a well-draining base of gravel and sand or stone dust. Dry laid stone walls, built on top of gravel-filled trenches that can double as drainage, are beautiful and fit in well with naturalistic landscapes.  A debate exists about the quarrying methods that are often used, but in some regions suitable stone is a by-product of farming and development, not quarrying.  You shouldn't feel guilty about "repatriating" such fieldstone in your natural habitat. Adding a water feature to the tiniest garden can yield substantial benefits.  More birds will drop in.  Moving water is an effective noise suppressant, and you'll notice the noise you do hear that much less.  On a small scale, consider a waterwall or other container water garden holding just a few gallons.  On a large scale, or a large scale construction project on a small property, a water catchment or bog for stormwater management is necessary, and may be required by law.  Aquatic plants and marginal plants (plants that inhabit sometime-submerged banks of ponds) will add beauty and habitat value to these features, but they will also do aggressive triple duty by removing excess nutrients and other contaminants from groundwater. And, of course, even a postage-stamp sized property awaits your personal touches: beautiful ceramic pots for your container plants; sculpture (defined as whatever you and your homeowners' association say it is); and trellises, arbors, fences, and lattice panels to support a year-round spectacle of well-behaved native vines, which can screen the smallest space imaginable. Conclusion By rethinking the role of the urban or suburban yard - selecting low-maintenance, environmentally responsible  plants and other materials, and placing them with care, we can all enjoy the benefits of sustainable landscaping on the largest and smallest properties.  These include reduced resource requirements, a positive environmental impact, and, best of all, a garden that gives back more than it demands.  These are the ingredients of a lasting garden - one that will be enjoyed by your grandchildren's generation and beyond.  Can you think of any better legacy to leave them?

Copyright 2004 by Nature By Design.  All rights reserved.  Reproduction or distribution requires the express consent of the author.