In the New Jersey Pine Barrens this carpet of sedge, Carex pensylvanica, is naturally occurring and requires absolutely no maintenance.
MORE AND MORE, garden plants are being used not just for aesthetic reasons but also for ecologically friendly purposes, encompassed by the relatively new term ‘functional horticulture’. Several applications of functional horticulture, including lawn replacement, erosion control, habitat restoration, green roofs and rain gardens, are set to increase rapidly in importance and popularity as a greater number of gardeners wake up to their value. And increasingly, using native plants in the garden is an appealing option.
While a detailed account of such processes is rather beyond the scope of this book, given the amazing versatility and adaptability that grasses exhibit it will be no surprise to see them figure highly in these practical and often environmentally based horticultural applications—many of which are suitable for gardens of all sizes.
Found across many cultures and under most climatic conditions, lawns are among the most enduringly popular of garden features. Traditional, high-quality lawns can be very impressive; for instance, when surrounding historic buildings they create a clear feeling of open space and provide easy access for foot traffic. (Ironically, though, many of the best lawns prohibit foot traffic in order to preserve their pristine appearance and display them as horticultural showpieces.) Yet such superb lawns are mostly very demanding in terms of time and resources needed to maintain them.
Alternatives to regularly cut grass swards are valuable primarily when environmental or financial costs of maintaining the traditional lawn are unacceptably high, or where cultural or environmental factors such as deep shade or arid, dry conditions prohibit the successful establishment of a more traditional green sward.
Another powerful argument for alternative lawns comes from a purely aesthetic standpoint: sometimes there is little value in maintaining an unsatisfactory or average traditional lawn when a looser less formal finish, often termed ‘the meadow look’, makes for a more stimulating feature with much less effort on the part of the gardener. Many unsatisfactory lawns probably linger today simply because their owners are unaware of the alternative possibilities.
Indeed, I have long found that many traditional lawns serve little purpose and offer little value considering the level of attention and resources they demand. Think of the typical house, with a small lawn at the front of the property, which must be kept looking tidy but otherwise performs no useful or essential function except perhaps allowing access to the building or other garden areas. When the whole garden area is quite small, and consists of a small lawn, a narrow flowerbed or two and perhaps a hedge or foundation planting, the lawn takes up valuable space that could otherwise be devoted to more interesting plantings.
In mild and often wet conditions such as those found throughout much of the U.K., the average lawn may only need cutting during the summer months, and possibly a few waterings if not left to go dormant in dry summers (which would also lessen the need for regular mowing, if also lessening the aesthetic value). While still performing no real function, such a lawn may be less burdensome than one in such warm and dry conditions as found in, say, southern California, which would require far more mowing and especially irrigation in an area that is already short of such precious resources.
In Tenerife this lawn prohibits foot traffic and needs regular watering and attention to maintain its impeccable condition, unlike the carpet of sedge on pages 124–125.
While often serving little use from either a design or a practical viewpoint, en masse these traditional lawns consume a vast amount of resources that would be better conserved for use elsewhere. Simply removing the lawn altogether (perhaps along with all of the other too-small garden features), and replacing it with a single carpet-like planting of grasses as a ‘meadow’ through which other plants such as bulbs summer flowers, and shrubs can grow, not only reduces the workload but makes a far more successful garden feature. Pathways can dissect the ‘carpet’ wherever necessary for access or simply for passing through.
A variety of low-growing grasses can recreate the effect of traditional open lawn at a fraction of its maintenence cost. The hakone grass, Hakonechloa macra, used here at the front of the new glass-house at the RHS Garden Wisley, England, contrasts effectively with trimmed beech cylinders.
Suitable grasses for such alternative lawns are usually compact and evergreen, with spreading rootstocks that can effectively renew themselves to maintain a good, even cover much as a traditional lawn grass might do. Any grass or grass-like plant with this attribute is therefore a candidate, but in practice much depends on the amount of wear or foot traffic it is likely to receive; a more limited number of plants will accept regular trampling.
An excellent example is in fact not a true grass but the western meadow sedge, Carex praegracilis. Native to a large part of the western United States in a range of situations from coastal sand dunes to inland meadows, this sedge is being used successfully in many areas across the U.S. Like other forms of Carex, this spreading sedge makes dense cover, remaining green with enough water and eventually going summer-dormant in prolonged drought. At the University of California’s Leaning Pine Arboretum in San Luis Obispo, for instance, this meadow sedge is used as a regularly mowed lawn of considerable size—and its amazing adaptability has seen its use in many private gardens, where it can be cut on a regular basis, to the point where it becomes virtually indistinguishable from a more traditional sward. However, it is arguably at it most eloquent when forming a shaggy evergreen cover that is cut as rarely as once or twice each year.
Eschewing a more traditional layout, Dave and Rainie Fross have planted a private garden in Arroyo Grande, California, with a system of informal pathways threading their way unhurriedly though grassy plantings. The result is a superlative essay in achieving the natural meadow effect, where plantings of Carex praegracilis are allowed to grow unchecked by the lawn mower, requiring perhaps a once-a-year trim, to produce a lush sward that is highly pleasing and entirely appropriate to its place and function.
The mondo grasses are often used as replacement covering, especially in shade where traditional grass swards will not survive. Ophiopogon planiscapus will make superb cover even in dry shade under trees, and needs virtually no maintenance, but will tolerate much less foot traffic than will the western meadow sedge. Ophiopogon japonicus ‘Minor’ has the smallest of leaves that make a complete cover only a few centimetres high, but again it is only for areas that are not regularly trodden.
Laying an alternative lawn is relatively easy. In many respects it is like planting any border or flower bed, but with a few special considerations:
Western meadow sedge, Carex praegracilis, can cover large areas and has a well-established reputation as a successful lawn substitute. Native to much of the western U.S. under a variety of conditions from coastal sand dune to inland meadows, it has a spreading rootstock that allows it to withstand regular cutting and a substantial amount of foot traffic. In the private Los Angeles garden on the right, the lawn is composed entirely of Carex praegracilis, irrigated as necessary with grey water from inside the house.
Carex praegracilis (above, towards the back) is used as part of the meadow matrix of grasses and sedges to lend a softer, more relaxed feel to the private garden of Dave and Rainie Fross.
• Remove any existing turf and loosen ground if compacted, then rake and prepare to a reasonably level finish.
• Avoid too fussy an outline; circles and gently curving edges are more satisfying and natural looking. Better still, to create a great sense of space, treat grasses as you would a wall-to-wall carpet indoors; plant right up to other features or boundaries, avoiding a clear edge.
• If possible, use smaller plants at high density, rather than a smaller number of larger plants, to make their establishment noticeably quicker.
• For a more traditional-lawn-like finish, especially one that is to be trimmed regularly, take care to plant at the same spacing throughout to provide the most even cover in the shortest time.
• After planting, use a surface mulch such as bark or gravel to allow the area to be used more quickly.
• Pathways, if needed, can be made from the same material as the surface mulch and allowed to meander through or around the new planting.
• Bear in mind that many lawn alternatives will need a little trimming. Some like Carex and Deschampsia will need a once-a-year cut using a trimmer for the shaggy meadow look, though they will accept more regular cuts with a lawn mower set relatively high. Others such as Ophiopogon planiscapus will virtually never need trimming.
As our homes and gardens extend outwards, they are in ever-closer proximity to beaches and their shifting sands. Consequently, plants once regarded as ‘weedy’ beach grasses of no real value are now seen as valuable tools that can solve a problem without recourse to often unsuccessful and always expensive engineered solutions of block and concrete. For instance, Panicum amarum, a coast-adapted species from the Eastern Seaboard of the United States, is both a beautiful and a practical choice for stabilization in these areas.
While a vigorous, self-renewing, dense, spreading root system may not characterize the ideal garden plant, it is essential if that plant is to deal effectively with unstable sand or soil. For example, on the beaches around Poole in Dorset, England, as in many other places lyme grass, Leymus arenarius, and other specially adapted beach grasses such as marram, Ammophila arenaria, help to stabilize and control the movement of the sand dunes, in the process creating a more stable environment for themselves and other wildlife.
Not all of us can live on a beach, but many gardens have soil banks in varying degrees of steepness which in many respects are similar to the shifting sands; soil banks are known for their ability to slip, especially in wet weather. Such problems are often controlled by engineered solutions such as retaining walls, which are never cheap, frequently ugly and difficult to disguise. In many situations, even steep banks can be controlled and stabilized by the use of dense-rooting, mat-forming plants such as Carex praegracilis, Phragmites australis or Leymus arenarius, which cover the surface and whose robust root systems will bind the soil together.
With banks that are less steep, a much wider range of grasses—which do not necessarily need such a vigorous spreading root system—can be used successfully. Often in such situations erosion is principally a wind-related problem, especially prevalent with dry soils in that the wind will gradually carry off the top layers of soil over an extended period. Establishing any kind of cover will stop or slow this process and any of the grasses above along with Aristida, Nassella, Melica and Stipa can be used.
Planting a bank is not much different from any other garden planting. For best results, consider the following:
• The steeper the bank, the more a vigorous root system is needed.
• Always use beach grasses for shifting sand, as they are adapted for such extreme conditions.
A steep bank between a private garden and a public highway in Monterey, California is prevented from slipping or eroding by the use of a native sedge, Carex praegracilis, which in its summer-dormant state mirrors the surrounding hillsides almost perfectly.
Lyme grass, Leymus arenarius, helps to stabilize and conserve the sandy dunes on a beach in Dorset, England.
• Quick establishment is always the goal, so plant at greater densities, perhaps using twice the usual recommended number of plants per square metre.
• A greater number of smaller plants will often establish and make a complete cover more easily than fewer larger plants.
• On steeper banks, or where loose soil is inclined to move around, use a covering mulch of matting that can be pegged down onto the soil. Netting can also be used if appropriate.
The term ‘habitat restoration’ usually describes the returning of an area to the vegetative population that occupied it at some point in the recent past. Often this involves removing existing aggressive exotic species and replacing them with native plants that were themselves gradually displaced by the colonizing exotics. It is often carried out in areas where there has been direct, frequently short-term, human interference such as the laying of pipelines, civil engineering work or even the building of new homes; after these projects end, it is desirable to return the area to something resembling its original natural state. Sometimes ‘sitespecific’ projects are carried out; when an area is due to be disrupted, plants (usually native) are collected, propagated and then later returned to a site once work has been completed.
On the coastal fringe of Monterey, California, in the narrow strips between a golf links and the ocean, garden designer Fred Ballerini and his team have piloted a successful scheme to turn this overlooked area back into its valuable habitat. The area had become covered with aggressive exotics such as the ever-popular ice plant which, while perhaps aesthetically pleasing to the casual eye, had effectively managed to stifle everything else in its path. As a first step, the ice plant covering much of the area’s forty acres was mechanically bulldozed and buried, with any regrowth being spot-sprayed and left as a mulch. As a result many native plants, including the saltgrass, Distichlis spicata, started an almost immediate and determined comeback. New plants germinated from the seed bank that was dormant but still viable in the underlying soil, and were quick to take advantage of the opportunity to recover lost ground. Several years on, the area now has a healthy mixed population of natives including grasses, sedges and rushes that are self sustaining and make a far greater contribution to the area’s biodiversity.
Stabilized sand dunes adjoining a coastal golf links in Monterey, California had become overgrown with exotics, such as the ice plant, to the detriment of native plants and grasses—until a rigorously planned programme of restoration brought about the successful return of many native grasses, sedges and rushes.
The native salt grass, Distichlis spicata, seen on the right emerging from the dead remains of ice plants, needed very little encouragement to return from the seed bank remaining in the sand.
In northern California’s Marin County, this garden designed by Bernard Trainor surrounds a new hilltop home and uses Californian poppy, Sonoma sage, and native grasses such as Nassella pulchra and Muhlenbergia rigens as part of a restrained and sophisticated palette—merging the newly designed elements with the natural landscape, and restoring some of what was lost during the building process. Photograph courtesy of Jason liske.
Historically, habitat restoration has been seen as the province of nature reserves and natural parks, rather than gardens and designed spaces. But as more and more homes infringe on natural areas, and as we gain greater understanding of the importance of preserving the natural landscape and maintaining biodiversity, an increased blurring of the lines between natural and designed areas will see the value and relevance of restoration projects increase many times over in the coming years.
In use for almost as long as humans have been building houses, green roofs—where living plant material is used as a roof covering for homes and buildings—are not exactly new. As urban, industrial areas take up ever more space, green roofs have seen increased popularity for their eco-friendly ability to modify and control major environmental issues such as the general loss of biodiversity, the creation of heat island effects and the increased risk from stormwater flooding.
With the construction of any building, from a basic garden shed to a multi-storey parking lot, the ground it occupies becomes unable to support any biodiversity. Installing a green roof helps to replace at least part of that loss, and making up for this building’s ‘footprint’ can be furthered through the appropriate use of locally native plants. Apart from their aesthetic appeal, such roofs’ demonstrable benefits include a reduction of energy consumption, and the control of stormwater runoff due to the sponge-like nature of an established green roof, which gradually releases water over a much longer period than a traditional roof would.
Green roofs are frequently described as either ‘extensive’ or ‘intensive’. Extensive roofs tend to cover larger areas, but with a shallow depth of substrate that restricts the choice of plant. Intensive roofs tend to be smaller in area but have a greater depth of substrate that allows a wider choice of plants, they are slightly reminiscent of more traditional roof gardens.
On a domestic scale, with a little knowledge and preparation, green roofs can be fitted to small outbuildings, garden sheds and even kennels relatively easily. As a green roof can add considerable weight to the loading of a roof structure, it is advisable to consult building professionals or specialist green roof firms before commencing any project.
A variety of plants including grasses and sedges make excellent green roof subjects, though as conditions can be difficult—extreme dryness, a shallow root run and searing temperatures are an issue in many situations—toughness is perhaps the plants’ prime requirement. Similar in some respects to lawn alternatives, a spreading, self-renewing, compact habit is a distinct advantage as this helps to create a dense self-sustaining mat that binds the roof together.
Roof gardens such as this one in downtown San Francisco are gaining popularity as their positive effects on human welfare and their value for energy conservation begin to be fully realized. Festuca and Carex combine in an attractive mosaic designed by Dave Fross.
As with banks and lawn replacement schemes, a great number of smaller plants makes a more satisfactory cover than a lesser number of larger plants. Planting density depends partly on the actual size of the plants, so that while larger plants may be used at (for instance) fifteen per square metre, smaller plug-sized plants might be used at twice that number.
Green roofs are an important part of the ethos of rain gardens, which themselves offer a complete alternative approach to using water in our gardens and urban spaces. Rain gardens challenge the more traditional view of water, so often regarded as either an individual ‘feature’ effectively divorced from the rest of the landscape or, especially in the case of urban stormwater, simply an irritation to be drained or culverted away at the earliest opportunity.
Low-impact design lies at the heart of the rain garden, where water is regarded as having a natural cycle that is both accommodated and used to benefit biodiversity. Natural water is often controlled through a series of features and plantings (often termed ‘bioretention’), much as a green roof might do but at the ground level and over a much wider area.
With their sponge-like ability to soak up moisture, to release water into the atmosphere, to filter and to cleanse, plants are an integral part of the bioretention process. Using plants at ground level (as opposed to on rooftops), eco-minded gardeners looking to conserve water can choose from a wider range of plants—including a palette of grasses that are both functional and beautiful.
The day of the native ornamental is drawing near.
—Douglas Tallamy, Bringing Nature Home
Gardening literature, and even culture, is littered with references to native plants as weeds, regardless of whether they are grasses or any other plants. And it is possible to understand this long-established link between weeds and natives; historically, gardens were intentionally artificial creations, filled with exotic introductions. Imposed on the natural landscape, these exotics necessarily displaced the native species which were regarded simply as unwanted plants. As one of the most common wild plants, grasses in particular have historically been removed in favour of non-natives.
This rain garden at the Tabor School in the United States was designed to catch and absorb water runoff from buildings and other structures, avoiding the need for expensive stormwater runoff systems and allowing the water to infiltrate the soil rather than being removed from the area where it is most needed. Photograph courtesy of Edmund C. Snodgrass.
These days, however, as we wake up to the true value of our natural systems and our collective impact on them, the definition of a weed is coming full circle to include many of those introduced exotic species, which often have aggressive tendencies to colonize, displace or disrupt the original communities of plants. An old saying has it that ‘a weed is a plant in the wrong place’, and for all its simplicity this has to remain among the most valid and accurate of gardening observations.
The iconic grasslands so often depicted in popular images of California are in fact largely composed of exotic European species, introduced in attempts to improve grazing. While these exotics supplant native grasses in most areas, highly serpentine soils present a barrier that allows the better-adapted native grasses to survive and even prosper.
WHAT IS A NATIVE? At first glance, and quite straightforwardly, a native plant could be regarded as coming from a distinct geographical area such as Europe or, more specifically, Germany. On the other hand, ‘exotic’ or ‘alien’ would describe a plant that did not naturally occur in that area but that had been introduced there (usually through human agency). A further category; that of a ‘naturalized’ species, describes an exotic that has been in its new home for sufficient time to be regarded, at least by some, as almost native.
However, given the vast areas, differing climates and local conditions that such broad terms encompass, these words can often be effectively meaningless and even counterproductive when it comes to the practice of garden-making and the process of choosing plants. For example a grass may be said to be a European native, but this does not necessarily mean it is a U.K. native and it is even less likely to be a native of a local coast-adapted community, say, in the county of Cornwall. In his excellent and thought-provoking Bringing Nature Home, Douglas Tallamy offers a far more useable definition by suggesting that “a plant can only function as a true native while it is interacting with the community that historically helped shape it.”
Vast expanses of locally native common reed, Phragmites australis, are havens for wildlife in the Neretva Delta in Croatia. When introduced in the United States, where P. a. is also native, this European form proved substantially less valuable to wildlife than its American counterpart. Photograph courtesy of Amanda Walker.
For instance, while many garden plants, including numerous grasses, can act as nectar suppliers to bees and butterflies, far fewer are able to serve as (equally essential) breeding host facilities for many of our native insects, or indeed to supply food for the numerous leaf-chewers which over long periods of time have developed relationships with specific plants that were locally native. To be of such value to the garden’s ecosystem, a plant must have a connection with the geographical area in which it is being planted; it has to be locally native.
Provenance, where a plant comes from, can be equally important to a plant’s biodiversity value. The common reed, Phragmites australis, is native to both Europe and the United States—but when the European form was introduced in America, it was found to sustain a much smaller insect population than the locally native form, despite being identical to the human eye. Cultivar selection, the process of encouraging ornamental qualities to gradually enhance the gardenworthy aspects of a native grass, does not appear to denude the grasses’ value as locally functioning natives.
Native plants bring a sense of timelessness and belonging to our gardens and designed spaces. On Ferndown Common, Dorset, England, during a heavy frost the purple moor grass, Molinia caerulea (above, middleground), appears in perfect harmony with its surroundings, creating a visually stunning masterpiece that is also a fully functioning part of the local biodiversity.
Plants that are native to an area are often the best choices for specific tasks that mirror their natural surroundings. The common reed, Phragmites australis, is ideally suited for use in stabilizing steep banks or other areas prone to slip, as it is supremely adept at colonizing similar areas in its natural environment.
WHY NATIVES? Grasses are present in just about every natural system in virtually every part of the world. While not all native grasses are gardenworthy, they offer numerous opportunities for gardeners to choose plants that have not only ornamental qualities but also a geographical connection to the area of their intended use. What’s more, using natives that have adapted and evolved in the local area removes the risk of gardeners introducing exotic escapees (more weeds), simply as those plants will have already been present as natives. When we accept the principle of ‘right plant, right place’, it is a short step to the appreciation that plants already thriving in the surrounding area are likely best adapted to the local climatic conditions, and therefore make the sensible, informed choice for garden use.
For purely aesthetic reasons, well-chosen and thoughtfully used native plantings can create an unparalleled sense of place, a sense of belonging that is almost impossible to emulate with an eclectic palette of plants chosen, however carefully, from different areas of the world.
Another (and perhaps the single most valuable) argument for using more native plants in our gardens is that they are more readily accepted as food, shelter and living space by a much greater percentage of the birds, insects and animals that, along with plants, make up the balance of the local communities—the biodiversity upon which all things ultimately depend. While at first glance our individual domestic gardens may seem relatively insignificant, while the amount of wild and natural space declines at a frighteningly rapid pace, our gardens play an increasingly essential role in the future wellbeing of our plant, insect and animal life.