Dirt has long gotten a bad rap. It’s messy, hard to haul and a lot less sexy than vegetable starts. However, as the foundation of the success of your summer vegetables, the garden bed is of the utmost importance to growing an organic backyard garden.

For a first-time urban farmer taking on the task of manipulating a grassy bit of yard into a vegetable bed, or a seasoned gardener who wants to re-vamp their soil, this guide will simplify the process of prepping your garden before you plant.

The dirt from a typical yard in Portland contains about 90 percent mineral residue and only 10 percent decayed organic matter. Plants thrive on organic matter, so a garden craves compost-heavy soils, which can be attained by purchasing a planting mix or soil amendment or by building up your soil by using a technique called sheet mulching.

Sheet Mulching: Low-Cost Alternative to Purchasing Soil

Volunteers sheet compost the Boise neighborhood community garden.
Volunteers use the sheet mulching technique at the Boise community garden.

Rodney Bender, the gardens programs manager of Growing Gardens, a nonprofit dedicated to planting vegetable gardens to combat hunger in Portland, prefers double digging and sheet mulching techniques as low-cost alternatives to purchasing soil.

This process involves removing the sod from your yard with a shovel and digging into the earth about two feet deep, turning it over and tilling it until it the dirt is loose and raised into a mound. Sheet mulching is basically adding a layer of decaying organic matter to your existing soil to improve the quality and create a vegetable-friendly environment. This is done by covering your dirt with a “weed barrier” of thick newspaper or cardboard to block the sun from reaching unwanted plant roots or seeds, topping it with compost and/or manure and then with a few inches of mulch (plant debris like grass clipping or straw).

If this labor-intensive process seems daunting, and you want to bring in a load of good, fresh earth to ensure a quality garden bed, Portland has some great resources to get the dirt.

Get the Dirt at Local Resources

Dean Innovations yard
Dean Innovations is located in East Portland's Lents neighborhood.

Locally-owned gardening stores and nurseries such as Portland Nursery, Pistils Nursery and Dennis’ Seven Dees sell bagged potting soil, which goes for about $8-12 for two cubic feet of yummy, compost-rich soil.

However, it will always be more cost-effective to buy in bulk, and it may even encourage some good old-fashioned neighborly dirt sharing.

Dean Innovations specializes in planting mixes, compost, gravel and bark dust for Portland yards. All of their topsoil, planting mixes and composts are created using 100 percent recycled yard debris from local residential garden excavations and organic vegetable matter. Naomi Montacre, the gardening guru of Naomi’s Organic Farm Supply, says that Dean Innovations has “taken it up a serious notch,” in terms of their commitment to producing top-quality organic soil and compost.

Dean Innovations recommends their “White Lightning” planting mix, which contains worm castings, fungi mycelium, mushroom compost, steer manure, pumice, local topsoil and compost. This formula was created specifically for Portland-area soils to enhance plant growth and crop yield. A cubic yard of the stuff goes for $44.

They also provide a “Premium Portland Blend,” which doesn’t contain the fungi, worm casting or mushroom compost but still is nutrient-rich and made from all local materials. The “Premium Planting Blend” will set you back $37 for a cubic yard.

Another excellent source of soil is Nature’s Needs, located in North Plains, which produces organic soil amendments made from the 35,000 tons of yard trimming and land clearing materials it collects each year. A cubic yard of their planting mix goes for only $20 a yard.

If proximity is important when choosing a soil supplier, Metro Recycling Info has a hotline, which offers a list of the closest resources based on your Portland ZIP code. Call 503.234.3000 for the dirt nearest you.

No matter where you decide to source your soil, Montacre suggests that, before you buy, you go out to the location and check out the product. Run your fingers through it to make sure there is no debris and ask the provider about the source.

Naomi's Organic Mineral Mix
Naomi's Organic Mineral Mix

“Use as much of your own dirt as possible since you know where it comes from. Then use amendments like nitrogen, kelp or minerals to produce dreamier soil,” she said.

Naomi’s Organic Farm Supply produces its own signature soil enhancer called “Naomi’s Organic Mineral Mix.” The five-part mix contains azomite volcanic ash, glacial rock dust, [dinosaur-era] jersey greensand, calphos rock phosphate and limestone for a mineral boost to your garden bed.

Other great soil amendments for Portland’s clay-rich soils are nitrogen, in the form of alfalfa and chicken manure, or kelp, which Montacre describes as “magical sea fairy dust for your garden.”

With a healthy and happy garden bed made from your very own dirt, local compost and soil amendments, you have created the foundation for a summer of yard-fresh veggies.

Happy digging!

Correction 6/6/11: The article originally stated that Nature's Needs was located in White Plains. We have corrected it to North Plains.