spaces garden edible dirt layering diagram
Image: Carl Wiens

Layering can help you create the best growing conditions for your vegetables by keeping grass and weeds out and nutrient-rich compost in.

Know Your Levels

Most vegetables need a slightly more alkaline environment than our native soil to reach their full potential. The soil here tends to be on the acidic side, which is great for growing rhododendrons, primulas and other flowering plants, but it’s not as conducive to growing vegetables. Mixing agricultural limestone (available at nurseries) into your soil will help lower the acidity level, but the exact amount you need to add will depend on your original levels.

To test pH levels, take a sample from the proposed site to a professional lab, like Wy’east Environmental Sciences (2415 SE 11th, 503-231-9320) If you’re planting within three feet of an older home, have them also test lead levels (lead paint was legal before 1978). A low-level lead test costs $20, and pH levels can be tested for $15.

Prep Your Bed

Next up, ready the area to create a bed where vegetables can flourish. Raised beds will help your vegetables thrive, warming the soil earlier in spring and vastly improving its drainage. Root out perennial weeds from your plot, including dandelion and quackgrass, and if the soil is wet and clumpy, toss a tarp over it for a few weeks to help dry it out. Then, rough-chunk your soil into clods with a shovel and turn the clods over, grass-side down.

Level the surface by filling in the cracks between clumps. Compost is the best material to use for this. Then spread newspaper (skipping the slick ads) six layers thick over the whole thing, overlapping the sheets substantially so you can be sure to smother any remaining grass and weeds below. Be methodical: There is an art to doing this without leaving gaps.