Hardscape—Terraces, Paths & Walls
By Sonoma County Master Gardener Steven Hightower
Landscape Architects and others in the landscape design field use the terms “softscape” and “hardscape” to distinguish between plants and soil work and all the other “hard” elements of landscaping. A simple definition of “hardscape” is anything in the landscape that is not plantings or earth works.
Some people might say “why do you want hardscape—a lot of hard, empty bits and parts in your garden”? They might feel that it’s unnecessary—even an intrusion into the land of plants.
So what does hardscape bring to the garden, and why not have all plants? First, open areas provide contrast and interest to vegetative spaces. Second, they provide areas for human activity in the garden, such as sitting to read, gathering for parties, grilling and eating. Third, of course, we need ways to move around in the garden—paths of stone, gravel or brick provide better footing, aren’t muddy in the wet, and look good. Finally, hardscape generally requires less maintenance, and fewer consumables such as water and fertilizer. While hardscape needs to be maintained, it does not require the regular care that plants do. You can go on vacation without worrying about your hardscape!
Thus, hardscape is an important part of landscape design—the bones, or the armature, of a garden. Its flagged patios, pebble mosaics, bricked open areas, packed gravel walkways, and natural stone—walls, benches, seats, landscape features—create the structure through which to weave the combinations of trees, plants and shrubs into the garden whole.
There are a wide variety of hardscape materials from which to choose—stone, brick, colored concrete, gravel, crushed rock, packed decomposed granite and more. Personally, I’m a stone freak—perhaps I was a troll in a past life. Stone connects the garden to the land, since stone is of the land. It’s a natural material that complements plants, lasts forever and is intrinsically beautiful. Flagstone terraces, high walls combining large vertical granite stones with small fieldstones, low traditional dry-laid walls, outdoor fireplaces and fire pits, fountains and waterfalls, rock paths and walkways—all seem to me to be a wonderful weft for the warp of landscape of plants, and further enhanced when combined with other natural elements such as wooden pergolas, woven branch fences and antique ornaments or placed objects.
Hardscape should relate to the style of house. A colonial or Georgian house would dictate brick or cut stone—something with some formality. A farmhouse in the Sonoma countryside would combine well with fieldstone walls and paths of flags or flat river stones set in gravel. A Craftsman-style house might call for a pattern of square and rectangular stones, and walls of cut or ashlar stone, or brick. My own Mediterranean-style house blends well with terraces of large flagstone set in sand, fieldstone walls, and paths and open areas of smaller flat stones and crushed Sonoma Gold rock from the Nun’s Canyon quarry across the valley.
It is effective to evince a sense of belonging to the natural landscape. For example, the Sonoma hills that surround my house are dotted with moss and lichen-covered grayish granite boulders, and the Nun’s Canyon quarry on the hillside just across the valley is a slash of gold. So we used boulders similar to the local fieldstone for placement stones, full-color bluestone flags (versus, say pink Arizona sandstone), dry-laid fieldstone walls and crushed gold quarry stone-all of which tie the hardscape back to nature.
Hardscape can help you divide the landscape into a collection of “rooms” or sequence of gardens. This is a popular methodology—it provides separate spaces for different activities, and a sense of surprise or discovery in moving from room to room. Stone walls or hedges act as room dividers, and steps and paths act as transitions between these rooms, as well as the means of moving between them.
Patios & Terraces
How a patio or terrace will be used in part should dictate your choice of paving material. Flat stones with mortared joints or sand-set brick are preferable for areas close in to the house, entries, and higher traffic areas. Irregular, dry-laid stones, crushed rock or packed decomposed granite are great for garden paths and casual areas. Dining areas or a seating terrace can be on stone, gravel or crushed rock, or wooden decking, depending in part on the furniture.
Also consider color, porosity, and density when choosing material. A light-colored stone or gold crushed rock may brighten a dark area, but could also create glare in an open sunny area, where a darker material might be preferable. Patios or terraces of stone or brick are most ecologically laid in sand, or decomposed granite, to allow natural drainage and airflow to the underlying soil to occur, and prevent runoff.
In a natural setting (again, depending on location and architectural style) where a more rustic look is desired, dry-laid walls (or stone walls that mimic the look of dry-laid) are most appropriate. The stones are simply stacked without mortar, and usually battered back at a slight angle into the hill to better resist gravity. One of the beauties of dry-laid walls is that they do not require a drainage system behind them, as water can seep through the joints between the stones. They can also flex and move in expansive soil conditions, without the cracking that can occur in mortared walls. Small plants—thyme, rosemary, or capers—can be planted in crevices in dry laid walls, which “melds” the walls into the garden, giving them that characteristic, been-there-forever look. Dry-laid walls should not exceed about 3 feet in height; beyond that, they can become unstable.
Taller walls, walls in slopes or unstable ground, and retaining walls should be mortared. A dry-laid look can still be achieved in a mortared wall, with the mortar holding the outermost layer “hidden” and not showing in the cracks between stones. Walls composed of all or many very large stones are incredibly dramatic and beautiful, but expensive and difficult to build, due to the enormous weights involved.
Paths and Steps
Paths need to be stable, easy to walk on, and ideally look like they belong. Again, a sense of fitting in with the natural landscape is important. Gravel, crushed rock and decomposed granite paths should be edged, either in iron, or one of the wood composites. Dry-set paths of flagstone should use thicker stones—2” plus. Stone steps need to be set in concrete for stability, unless they are fairly massive (5-6” thick) stones that will be stable on the ground or a bed of crushed rock. Stones, concrete steps or large wood pieces (such as sections of railroad tie) can be used in combination with crushed rock or decomposed granite to create larger steps.
Combinations of two or more materials—irregular flat stones set flush in pea
gravel; recycled brick combined with flat river rocks, mosaics of white stones set flat with black on edge; wooly thyme or Corsican mint interplanted in sand-set flagstones can provide an interesting effect.
The use of large natural stones or boulders as pure design elements in the garden—rocks for rocks’ sake alone—lift it out of the ordinary: enormous granite fingers; limestone posts; large half-buried mossy fieldstones; a stacked-slab cairn; a free-standing three-stone arch; or sculptural stone groupings. These singular massive elements create focal points for the garden that make them “pop” with unusual interest. The Japanese are masters in the use of stones and boulders in the garden. Stone or wooden bridges, benches, rock brick or steel walls and borders all provide additional contrast and interest.
So, if you’re designing a new garden, or looking to rehabilitate a portion of one already in existence, think of the hardscape components just as carefully as you consider what trees, shrubs and plants you want to put where. In the end, you’ll have a more integrated, harmonious design, less maintenance and a more interesting garden!
Pebble mosaics are an ancient and beautiful form of hardscape, consisting of vari-colored pebbles and stones set in mortar in patterns.
Glen Ellen mosaic artist Anne Ziemienski has been working in both pebble and marble mosaics for many years, and provided us with insight into the ins and outs of using pebble mosaics in landscaping. Her work has been featured in the New York Times, Great Gardens, and Sonoma Magazine. Her interest in this ancient artform—pebble mosaics probably date to 2000 years BC—stems from childhood years spent living in Rome, and later time spent in the Middle East. "Mosaics used in a landscape add mystery", she says, and adds "they are so harmonious when softened at the edges with low plantings".
Geometric patterns tend to dominate, due to the nature of the material, along with symbols or icons repeated on a background, or simple floral patterns. We asked her the most frequent use of pebble mosaics in hardscaping—"First and foremost as fountain surrounds" she replied. "For pathways—going from one place to another, or to create a small 'room' or a 'carpet' on a background of other hardscape, such as decomposed granite or fine gravel."
There are two methods of creating pebble mosaics, according to Ziemienski—stones directly placed, section at a time into wet mortar, or created in inverse in sections, with the sections fit together set in sand in the garden. In the former, small areas at a time are spread with a layer of wet mortar, pebbles inserted in the pattern into the mortar, and the section leveled with a tamping board.
In the inverse method, forms of the section are created, a layer of sand placed in the form, the pebble pattern placed into the sand, and mortar spread over the whole. When set, the section is removed from the form and flipped, the sand washed off, and the sections are then pieced together in a base of sand in the garden. She works in the latter method, which she learned of through the work of reknowned British pebble mosaicist Maggy Haworth—"It gives greater control, allows for finer patterns, and results in a smoother, more level finished surface."
What does it cost, we want to know. "It can be expensive in larger amounts" she replies. "Professionally done and installed, a ballpark figure is $100-150 per square foot, depending on pattern complexity and site conditions." What if a gardener wants to do it themselves, we wonder? She replies that materials—pebbles, sand and mortar—are readily available and reasonably affordable at local building supply houses. "If the gardener provides the creativity and labor, it doesn't have to be that expensive" but warned "it's heavy, back-breaking work. Still, if you start with a small area, it's doable, and can be very rewarding".
The artist closes with both a heartfelt recommendation and a warning—"pebble mosaics are the most wonderful feeling on bare feet—like the best foot massage—but they can be killer on high heels".
Anne Ziemienski's work can be seen on the website which she shares with her artist husband Dennis.
All images in sidebar © Anne Ziemienski