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The Workbench: Make a raised planter box


If you're looking for a way to conserve water, combat gophers and save your knees, a raised planter box may just be your next summer project. You can make one out of redwood lumber, reclaimed wood or even a galvanized steel water tank if you're short on time and tools.

Jose Hernandez, general manager for Sonoma-based Waldron Landscape, has built plenty of traditional raised beds over the years but suggests the latter as a quick, simple solution.

Start with a 1- or 2-foot-tall galvanized steel water tank, available at farm supply stores such as Western Farm Center in Santa Rosa. Drill a series of drain holes in the underside, add a base of rock and fill with organic bedding soil.

If you plan to set it set on a hard surface, place a clay tile or cobblestone at each corner to allow for air circulation and free drainage. Drip lines can also be installed discretely through one of the bottom drain-holes to eliminate the visual distraction of lines draping over the top.

For a finishing touch, some people like to paint their tanks, but be sure to use a galvanized metal primer for proper bonding.

<b>Redwood planter</b>

If you prefer a larger planting area or want to link several beds together, consider building a traditional raised redwood bed. Be sure to select all-heart redwood as the wood's tannin (responsible for creating the red hue) provides rot resistance and mitigates invasive termite infestation.

The size and shape of your planter box is generally dictated by the layout and available yard space. Some people prefer a series of square boxes accented around the yard, while others enjoy the efficiency of larger, 6-foot long by 2-foot-wide beds.

One-foot tall planters will suffice for herbs and some shallow root veggies, but most plants will require a soil depth of two feet in order to maximize their growth.

You will need the following materials for the larger bed:

-- Four 2'x12'x6' redwood planks for the sides;

-- Six 2'x12'x2' redwood planks for the ends and center cross-blocking;

-- Four 2'x2'x2' redwood struts for corners;

--- 36 1/4-inch lag screws or self-tapping bolts, at least 6" long;

-- 36 washers if using lag screws;

-- 72 square feet of galvanized hardware cloth;

-- 2 cubic feet of gravel;

-- 24 cubic feet of compost or planting soil.

Tools required include a drill, a saw, metal cutting shears and a socket or crescent wrench. Investing in a battery-powered drill will serve you well, not only in the garden but for myriad other around-the-home projects. If you don't have a saw, many lumber yards will cut your wood to size.

Start by stacking two of the 6-foot planks. To securely attach the upper and lower planks, insert a vertical 2'x2' or 2'x4' redwood strut at each inside corner and attach with 3" treated screws. Do the same with the 2-foot end planks.

If you favor the industrial look, use galvanized lag screws with decorative "bridge" washers. Or use heavy-duty, self-tapping wood screws such as FastenMaster brand's TimberLOK, which offer speedy installation with minimal visual attraction. Boxes of 50 screws come with handy hex-head driver drill bits.

Install mid-span cross-strut supports to minimize bowing due to soil and hydrostatic pressure. If you also would like to add slatted bottom supports, use scrap wood in 1'x6' or 2'x6' sizes.

Choose discarded 2'x6' deck boards if you would prefer an alternate recycled wood source.

If gophers and voles are a problem, turn the box over after you have completed your basic framing and install ?" galvanized hardware cloth to the underside.

Once the bed is complete, start by filling it 2 inches deep with gravel, reused shredded Styrofoam and shipping peanuts or both. Then top with locally sourced compost or organic raised-bed planting soil such as the Kellogg brand, available at most Northern California garden supply departments.

If you would like to add hot house or freeze protection, cut short lengths of 1" PVC pipe and secure in a vertical position to the sidewalls with metal straps. The number of hoops is a matter of personal taste. Then take a 3/4" PVC pipe and bow it to your liking, cut to fit and insert the ends into the 1" pipes.

Drape them with thick-mil plastic sheeting, then staple the plastic's linear edges to 1"x2" wooden strips and secure with screws for easy seasonal removal.

The mixed blessing of raised beds is their superior drainage, which creates optimal growing conditions but also requires more frequent watering.

Part-time Sonoma resident Annie Pivarski devised a brilliant plan to minimize water waste. She designed a series of cascading planters that step down a steep hillside. She drilled a series of holes at the leading edge of each planter and connected them with ?" plastic drip tubes. Instead of draining out the bottom, water is captured and carried through the drip tubes to irrigate plants in the next planter box.

(Thomas Wilmer has been a licensed general contractor since 1986. Contact him with questions or story suggestions at tomwilmer@aol.com.)