How to Turn a Lawn into a Garden | PNW Guide

Sheet mulching with cardboard and arborist wood chips for garden paths.

"Should I put cardboard over the weeds?" The answer is...it depends. The best method depends entirely on what you want the space to become.

First, Decide What You're Going to Grow

Before deciding how to kill your lawn, answer this question:

What do you want this area to look like in three years?

• A Pacific Northwest native planting?

• A vegetable garden?

• A wildflower meadow?

• An orchard?

• A mixed ornamental bed?

Each has different soil needs, so the "right" preparation method is different.

How to Turn a Lawn into a Native Plant Garden

This is where cardboard and arborist wood chips shine. Most Pacific Northwest native shrubs and woodland perennials evolved in forest and woodland-edge ecosystems. Those ecosystems naturally have soils rich in fungi, created by decades of decomposing leaves and wood. Wood chips help recreate those conditions. My favorite approach is:

The chipped area in the background was planted with native perennial shrubs. The foreground is a rain garden, before being planted with soft rush, camas, and spirea.

1. Spread a thin layer of arborist chips.

2. Cover with overlapping cardboard.

3. Add another 4-8 inches of arborist chips.

The bottom layer creates air pockets and protects soil organisms. The cardboard blocks existing vegetation. The top layer keeps the cardboard moist, prevents it from blowing away, and gradually feeds the soil food web. When it's time to plant, simply cut an X through the cardboard and plant directly into the existing soil.

Preparing a Vegetable Garden

Vegetables evolved in disturbed soils that are more bacterial than fungal. That means they usually respond better to compost than thick layers of wood chips. If you're creating vegetable beds, I generally recommend:

• Remove persistent perennial weeds first.

• Add several inches of compost.

• Use compost or straw as mulch around crops.

Wood chips are still wonderful...just not usually inside annual vegetable beds.

Instead, use them on pathways where they'll suppress weeds, reduce mud, and slowly improve the soil underneath.

Preparing a Wildflower Meadow

Meadows are different again. Many meadow plants actually thrive in lean, relatively low-fertility soils. Adding large amounts of compost can encourage grasses and aggressive weeds that outcompete wildflowers. Depending on the existing site, you may be better off removing sod, controlling perennial weeds, and sowing directly into prepared soil rather than building up organic matter.

Methods for Removing Grass and Weeds

There isn't one "correct" way to kill grass. Each method has advantages.

Cardboard Sheet Mulching

Best for:

• Shrub beds

• Native plantings

• Areas you won't plant immediately

Pros

• Inexpensive

• Improves soil over time

• Protects soil structure

• Encourages earthworms

Cons

• Doesn't remove perennial weeds with deep roots.

• Weed seeds already in the soil remain viable.

Occultation and Solarization

Occultation uses black plastic or a heavy opaque tarp to exclude light. Without sunlight, existing vegetation dies. It works surprisingly well on lawns and annual weeds. However, it doesn't eliminate dormant weed seeds.

Solarization uses clear plastic to trap solar heat. The goal isn't to block light—it's to cook the upper few inches of soil. This method can kill weed seeds, diseases, and some pests.

The catch? It works best where summer temperatures are consistently hot. In much of western Oregon, our summers usually aren't hot enough for reliable solarization. In my own backyard, clear plastic mostly created a giant greenhouse where the weeds grew faster.

Gardening advice often comes from California, Arizona, or the Southeast. Those methods don't always translate to our climate.

Sod Removal

Sometimes the simplest option is the best one. If you're converting a lawn into planting beds, removing the sod physically eliminates the grass along with many of the weed seeds concentrated in the turf layer. It's more work up front but gives immediate results. Afterward, mulch according to what you're growing:

• Arborist chips for native gardens and shrubs

• Compost for vegetables

• Minimal amendments for many meadows

  
  

Which Lawn Removal Method Is Best?

The internet loves simple formulas:

"Put down cardboard and six inches of mulch."

"Cover it with plastic."

"Till everything under."

None of those methods is always right. The best method depends on your goals, your weeds, your soil, and your climate. A gardener who wants tomatoes should prepare the site differently than someone planting Oregon grape, and both should prepare it differently than someone establishing a native meadow. The trick isn't finding the one perfect method. It's choosing the right method for the garden you're trying to create. You can learn more about soil biology and how to support the life that supports your plants by reading Dig In, Gently.

Pacific Northwest Tip

Most gardening advice online isn't written for western Oregon or Washington.

Our cool, wet winters, dry summers, fungal-rich forest soils, and long rainy season make many national recommendations less effective—or even counterproductive. Before following advice, ask whether it was developed for a climate like ours.