Rock Garden

Landscape Smart : Episode LDS-104 -- More Projects »
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This unused, barren patch of property will soon become a beautifully landscaped gathering place for three families.
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On a scale of 1 to 5, the difficulty rating for this project is 5 (difficult) because of the size of the boulders. Just ask show host Ken Bastida!


The overall goal of this project is to create a relaxing, low-maintenance garden--nothing elaborate. As homeowners Miles and Piper Berger explain it, three related families live adjacent to one another on separate parcels of land. They'd like to take one piece of property not used by the families, says Miles, and design a garden that will knit the different backyards together to make a cozy spot that all three families can enjoy.
Landscape architect Casper Curto has the perfect solution. He suggests a natural rock garden, which will include a winding path with stairs that lead to a sitting area. Rock gardens help create a sense of being up in the mountains, he says, and should be designed with these principles in mind:
  • Make sure the rocks you use are the proper proportion for the area you're landscaping. If they're the wrong size, the space will feel too empty or too full.
  • Create a path that meanders through the garden. After all, in nature, rocks land where they may.

Curto estimates that it would cost $5,000 for a professional landscaper to complete this job. A homeowner, he says, could do it in a couple of weekends for $900 to $1,000 in materials and $400 in plants--about $1,400 total.
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Figure A
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Figure B
Step One: Building the Stairs

Because the future garden sits at the top of a rocky slope, the first thing Curto does is make stairs. He uses a jackhammer to dig into the heavy, compacted soil, excavating ledges on which stair timbers will be placed. (If the soil were more pliable, a pick would suffice).
Next, he flattens the ground where the stairs will be built (figure A) and lays in 6- by 8-foot pressure-treated Douglas fir beams (figure B). Any pressure-treated wood that's rated for ground contact will work.

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Figure C
Tip: If stair timbers need to be cut to a certain length, apply wood preserver on the ends to prevent rot.
Using a high-powered drill and a 5/8-inch bit, Curto creates a couple of holes in each timber for three-foot pieces of rebar (steel rods with ridges, typically used in reinforced concrete), which is hammered through the beams to anchor the stairs in the soil (figure C).
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Figure D
To help prevent erosion on the hillside and keep the stairs in place, he positions rocks along the sides. Finally, he fills in the treads of the stairs with the same gravel that will be used in the rock garden above (figure D), an important step for assuring continuity throughout the landscape design.

Step Two: Laying Out the Rock Garden

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Figure E
Now it's time to make the rock garden. Begin by outlining the garden path with an environmentally-sound water-based spray paint. Choose a color such as bright orange that will show up well against the soil (figure E). If you make a mistake with the paint, just cover it with dirt and respray.
Once the path is winding along the way you want it to, place stones in a random but balanced order around your outline. Rocks shouldn't be the same size or too evenly spaced--if they are, the garden won't look natural. Step back, take a look and see what you think.
Tip: When placing large stones, dig a hole and bury part of the rock for stability. Doing this will also make the stone look as though it's been there a long time.
Planting Plan

To give the garden an alpine feel, Curto selects hardy, low-maintenance plants:

  • Peruvian lily (Alstroemeria), Zones 7-10, is a good choice because of its long period of bloom and vibrant color.
  • Yarrow (Achillea 'Fireland'), Zones 4-8, is easy to grow and available in a range of colors and heights.
  • Fountain grass (Pennisetum), Zones 8-10, grows three to four feet tall and adds texture, color and movement to the rock garden.
  • Dietes (Dietes vegeta), Zones 9-10, blooms spring through summer, with foliage that's attractive all year round.
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Peruvian lily (Alstroemeria), Zones 7-10, is a good choice for long blooming time and vibrant color.
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Dietes (Dietes vegeta), Zones 9-10, blooms spring through summer, and the foliage is attractive all year round.

The plan is to put specimens next to the stones in such a way that they won't grow large and dwarf the rocks. When the garden is finished, the plants should appear as if they grew there wild.
Tip: Tuck plants at the base of boulders for a natural look, and mix splashes of color with foliage.

Step Three: Building the Path

With the plantings in place, Curto sets to work installing the large pieces of flagstone in the outlined garden path. He lays all the stones in the desired pattern, then lifts each flagstone individually and digs out the soil beneath to half-bury the stone and make a level walkway.

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Figure F
To finish, he scatters a two-inch layer of gravel over the soil and around the plants (figure F). The stone mulch will discourage weeds and enhance the alpine look.
Tip: Don't make the gravel layer around plants too deep--it will be difficult to walk on because you'll sink into the small stones.
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The finished garden.
The Completed Rock Garden

This area's potential has now been fully realized, with the completion of a separate garden room--a beautiful rocky retreat--on the property.

Guests
Casper Curto
Landscape Designer and Contractor, Casper Landscape Design
7612 Hillmont Dr.
Oakland, CA 94605
Phone: 415-383-2228
Fax: 510-636-9270

Richard Ward
Succulents Expert / Nurseryman, The Dry Garden
6556 Shattuck Ave.
Oakland, CA 94609
Phone: 510-547-3564
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