Seattle Soil Improvement: Composting

Good soil is the foundation of every healthy yard. In Seattle, many homeowners struggle with compacted, rocky, or nutrient-poor soils left behind by decades of construction and development. One of the simplest and most effective ways to improve that soil is through composting.

Compost is decomposed organic matter—think food scraps, yard waste, and fallen leaves—that turns into a dark, crumbly soil amendment full of nutrients and beneficial microbes. Adding compost to your yard improves fertility, helps with drainage, and supports the living organisms that make soil healthy.

Why Compost Matters in Seattle

Seattle soils are often acidic, low in organic matter, and prone to compaction. Compost helps balance these problems by:

Feeding the soil: Provides slow-release nutrients that plants can use year-round.

Improving structure: Loosens clay soils and helps sandy soils hold moisture.

Supporting soil life: Encourages earthworms, fungi, and microbes that make nutrients available to plants.

Reducing waste: Keeps food scraps and yard debris out of landfills, cutting methane emissions.

Managing stormwater: Compost increases the soil’s ability to soak up water, reducing runoff and flooding.

How to Make Compost at Home

What to Compost

Greens (nitrogen-rich): fruit and veggie scraps, coffee grounds, grass clippings.

Browns (carbon-rich): leaves, straw, shredded cardboard, small branches.

What to Avoid

Meat, dairy, oily foods (attract pests).

Pet waste.

Diseased plants or invasive weeds that could spread back into your yard.

The Basics

Layer greens and browns: Aim for roughly 1 part greens to 3 parts browns.

Keep it moist: Like a wrung-out sponge.

Turn or mix: Every few weeks to add oxygen and speed up decomposition.

Wait and harvest: Finished compost is dark, crumbly, and earthy-smelling.

Composting Options in Seattle

Backyard bin: Build or buy a compost bin for your yard waste and kitchen scraps.

Worm bin (vermicomposting): Great for small spaces and apartments; worms break down food scraps quickly.

Yard waste service: Seattle Public Utilities collects food and yard waste in green bins and composts it at large scale.

Community compost programs: Some neighborhoods and community gardens share bins and distribute finished compost locally.

Using Compost in Your Yard

Garden beds: Mix 2–3 inches into the topsoil before planting.

Lawns: Spread a thin layer (¼ to ½ inch) in spring or fall to improve turf health.

Mulch: Use compost as a top dressing around shrubs, trees, and perennials.

Soil improvement: Blend with existing soil in new landscapes to improve structure and fertility.

Conclusion

For Seattle homeowners, composting is one of the best tools for improving soil health. It’s simple, cost-effective, and sustainable. Whether you make your own, use worms, or rely on curbside collection, adding compost to your yard pays off with healthier plants, reduced waste, and stronger, more resilient soil.

Healthy soil starts with organic matter—so if you want to improve your yard, start composting today.