ShareThisMediterranean mounds or berms have become a popular part of water-wise gardens, taking the place of large sections of lawn.
A mound can add a focal point, often filled with year-round color, where there used to be solid green. They're called "Mediterranean" because they often use drought-tolerant, low-maintenance plants that grow naturally in a Mediterranean climate. In addition to helping drainage, the mound shape is inspired by how these plants would grow naturally.
Landscape designer Cheryl Buckwalter, co-author of the "Blue Thumb" blog and principal of Landscape Liaisons in Cool, Calif., offers this advice for anyone thinking about building a Mediterranean mound:
-- Function: What do you want the mound to be? It can increase privacy, add interest to a flat area or help direct water to a rain garden. This will guide you decide upon its size, height and shape.
Buckwalter suggests a mound 12 to 18 inches at the highest point, and four to five times as long as it is high.
"Consult licensed professionals if you want really large mounds, as they can require engineering, or if there are grading and drainage issues that need to be resolved," she added.
-- Soil: Once you choose a spot and shape, lightly dig up the soil to break up the surface before bringing in more soil to create the mound. If importing soil (either purchased or from another property), use clean topsoil free of rocks, roots and weeds.
"If soil has been excavated to make a walkway or patio, use that soil to make your mound," Buckwalter said.
Where the bottom layer meets the mound addition, mix the soils together for 2 to 3 inches. Then, continue adding more soil, spreading and shaping as you go.
-- Allow for mulch: If the mound is near hardscape such as a concrete patio or walkways, excavate enough soil to accommodate bark mulch.
Buckwalter suggests digging a shallow trench 2 to 3 inches below the level of the hardscape and 10 to 12 inches wide, tapering back from the hardscape toward the mound. "The excavated soil can be used for the mound," she said.
Once bark mulch is installed, this technique will help reduce the potential movement of mulch onto the hardscape, into the street and ultimately the storm drains.
-- Shaping: Mounded soil should be tapered from highest to lowest points so the transition is gradual between the existing grade and the slope of the mound.
"The softly tapered contours should make the mound appear as a natural part of the landscape," she said.
-- Settle the soil: Tamp the soil down lightly and smooth the top and sides with the back of a rake or use a landscape roller like the ones used to install sod.
-- Before planting: "To finish off the mound, I like to increase the soil's moisture level prior to planting," Buckwalter said. "To do this, the soil surface should be slightly loose so the water doesn't form a crust, preventing the water from soaking into the soil."
With a hose and shut-off nozzle, lightly spray the surface. Do this several times, allowing a soaking-in period between each time you spray with water to prevent erosion of the soil.
"Let the soil surface dry and you're ready to plant," Buckwalter said.
(Distributed by Scripps Howard News Service, www.scrippsnews.com.)
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