How to Start Composting in Seattle Backyard

Composting is more than just a sustainable hobby—it’s a powerful environmental practice that transforms kitchen scraps and yard waste into nutrient-rich soil, reducing landfill burden and lowering greenhouse gas emissions. In Seattle, where residents are deeply committed to sustainability and the city offers robust support for eco-friendly living, backyard composting has become an accessible and impactful way for homeowners to contribute to a healthier planet. With mild, wet winters and a thriving local gardening culture, Seattle provides ideal conditions for home composting. Whether you live in a single-family home in Ballard or a townhouse in Capitol Hill, starting a compost system in your backyard is not only feasible but highly encouraged by local ordinances and environmental programs.

This guide walks you through every step of starting and maintaining a successful backyard composting system in Seattle. From selecting the right bin and managing the local climate to avoiding common pitfalls and leveraging city resources, you’ll gain the knowledge and confidence to turn waste into gold—literally. By the end of this tutorial, you’ll understand how to create rich, dark compost that nourishes your garden, reduces your household waste by up to 30%, and aligns with Seattle’s ambitious Zero Waste goals.

Step-by-Step Guide

Step 1: Understand What Can and Cannot Be Composted in Seattle

Before you begin, it’s essential to know which materials are suitable for backyard composting in Seattle’s climate and regulations. Not all organic waste is created equal, and improper additions can attract pests, create odors, or slow decomposition.

Acceptable materials include:

• Greens (nitrogen-rich): Fruit and vegetable scraps, coffee grounds, tea bags (without staples), fresh grass clippings, plant trimmings, and eggshells.
• Browns (carbon-rich): Dry leaves, straw, shredded newspaper (non-glossy), cardboard (tape and labels removed), sawdust (from untreated wood), and small twigs.

Materials to avoid:

• Meat, fish, dairy, and oily foods: These attract rodents and raccoons—common in Seattle neighborhoods—and can create foul odors.
• Pet waste: Feces from dogs, cats, or other animals may contain harmful pathogens not destroyed in home compost piles.
• Diseased plants or weeds with seeds: Home compost piles rarely reach temperatures high enough to kill pathogens or invasive seeds.
• Coal or charcoal ash: May contain harmful chemicals.
• Glossy or coated paper: Often contains plastic or toxic inks.

Seattle Public Utilities (SPU) permits composting of food scraps—including meat, bones, and dairy—in curbside organics bins, but backyard systems should stick to plant-based materials to avoid attracting wildlife. Keeping your backyard pile simple and clean ensures safety, efficiency, and neighborly harmony.

Step 2: Choose the Right Compost Bin for Your Space

Seattle’s urban and suburban landscapes vary widely, so selecting the right bin depends on your yard size, aesthetic preferences, and how much waste you generate.

Open Pile (No Bin): Ideal for large yards with ample space and low wildlife pressure. An open pile is the most cost-effective option—just designate a corner of your yard and layer materials. However, it requires more maintenance to turn and may attract animals if not managed properly.

Enclosed Tumbler Bin: A rotating drum that speeds up decomposition by making turning easy. Excellent for small yards, patios, or residents who want a tidy, odor-free system. Tumblers retain heat well, which is helpful during Seattle’s cooler months. Look for models with dual chambers to allow one batch to cure while you add new material.

Stationary Bin (Wood or Plastic): The most popular choice among Seattle homeowners. Wooden bins, often DIY-built from pallets, blend naturally into gardens. Plastic bins, like the FCMP Outdoor IM4000, are durable, rodent-resistant, and easy to assemble. They offer good airflow and insulation, making them ideal for Seattle’s damp climate.

Worm Bin (Vermicomposting): Perfect for apartment dwellers or those with minimal outdoor space. Worms (specifically red wigglers) break down food scraps quickly and produce nutrient-dense castings. While technically not “backyard,” many Seattle residents use worm bins on balconies or in garages. Keep the bin shaded and moist—ideal for Seattle’s overcast weather.

When choosing, consider:

• Size: Aim for at least 3 cubic feet to maintain heat and microbial activity.
• Drainage: Ensure the base allows excess moisture to escape.
• Access: Look for easy-opening lids or removable fronts for turning and harvesting.
• Material: Avoid bins made from recycled plastics that may leach chemicals over time.

Many Seattle residents qualify for discounted compost bins through SPU’s Compost Bin Discount Program, offering bins for as low as $25. Visit their website to check current availability.

Step 3: Select the Ideal Location in Your Backyard

Location is critical for successful composting. In Seattle’s rainy climate, drainage and sun exposure must be balanced carefully.

Choose a spot that is:

• Level and well-drained: Avoid low-lying areas where water pools. Excess moisture slows decomposition and can create anaerobic conditions, leading to foul smells.
• Partially shaded: Seattle’s frequent rain and cool temperatures mean full sun isn’t necessary. A spot with dappled shade or morning sun helps regulate temperature without drying out the pile.
• Close to your kitchen: Convenience encourages consistency. A bin near the back door makes it easier to add scraps daily.
• Accessible year-round: Avoid placing your bin where snow or mud may block access in winter.
• At least 10 feet from property lines: To prevent neighbor complaints and comply with city guidelines.

Many Seattle gardeners place their bins near vegetable beds or fruit trees so finished compost can be easily transported. If you’re concerned about aesthetics, screen the bin with native shrubs like salal or sword ferns—they’re low-maintenance and thrive in Pacific Northwest conditions.

Step 4: Build Your Compost Layer by Layer

Successful composting relies on the right balance of carbon and nitrogen—often called “browns” and “greens.” Aim for a ratio of about 3:1 (browns to greens) by volume.

Here’s how to layer your pile:

1. Start with coarse browns: Place a 4–6 inch layer of twigs, straw, or shredded cardboard at the bottom. This promotes airflow and drainage.
2. Add a layer of greens: Sprinkle 2–3 inches of fruit/vegetable scraps, coffee grounds, or grass clippings.
3. Top with browns: Cover the greens with another 4–6 inch layer of dry leaves, shredded paper, or sawdust. This prevents odors and deters flies.
4. Repeat: Continue layering, keeping greens covered at all times. Think of it like building a lasagna—alternating layers of moist and dry ingredients.
5. Maintain moisture: Your pile should feel like a damp sponge. Seattle’s rain often provides enough moisture, but during dry spells (late summer), lightly water the pile.

Pro tip: Chop or shred larger items (like corn cobs or avocado pits) to speed up decomposition. Smaller pieces have more surface area for microbes to work on.

Step 5: Turn and Maintain Your Pile Regularly

Turning your compost introduces oxygen, which accelerates decomposition and prevents odors. In Seattle’s cool, wet climate, decomposition slows in winter, but regular turning keeps the process active.

Turn your pile every 1–2 weeks during spring and summer. Use a pitchfork or compost aerator tool to mix the outer edges into the center, where heat and microbial activity are highest.

Signs your pile needs attention:

• Smells bad (like rotten eggs): Too wet or too many greens. Add more browns and turn immediately.
• Not heating up: Too dry or not enough greens. Moisten and add nitrogen-rich materials like coffee grounds or fresh grass.
• Attracting pests: Food scraps are exposed. Cover with a thick layer of browns or switch to a sealed bin.

During winter (November–February), composting slows but doesn’t stop. Insulate your pile with a tarp or straw bales to retain heat. You can still add materials—just expect a longer curing time.

Step 6: Harvest Your Compost

Compost is ready when it’s dark, crumbly, and smells earthy—like forest soil. This usually takes 2–6 months in Seattle, depending on season and maintenance.

To harvest:

1. Stop adding new material to the bin 4–6 weeks before harvesting to allow the final batch to cure.
2. Use a screen or sifter (a ½-inch mesh works well) to separate finished compost from large, undecomposed pieces.
3. Return any large chunks to the active bin to continue breaking down.
4. Store finished compost in a covered container or directly apply it to garden beds.

Apply compost in early spring or fall, spreading a 1–3 inch layer over soil and gently working it in. Use it for vegetable gardens, flower beds, potted plants, or as a top dressing for lawns. Avoid piling it against plant stems to prevent rot.

Best Practices

Manage Moisture Like a Pro

Seattle’s rainfall can be a blessing and a curse. While moisture is essential for decomposition, too much water suffocates microbes. Ensure your bin has drainage holes and avoid placing it under downspouts. If your pile becomes soggy, mix in shredded newspaper or dry leaves to absorb excess water.

Balance Your Inputs

Many beginners add too many kitchen scraps and not enough browns. A common mistake is dumping coffee grounds daily without adding carbon material. Always keep a bin or container near your kitchen for collecting browns—shredded cardboard is ideal. Keep a small stash of dry leaves or straw in a garage or shed for quick access.

Prevent Odors and Pests

Odors are a sign of imbalance, not inevitability. Always bury food scraps under 6 inches of browns. Avoid adding citrus peels in large quantities—they’re acidic and can disrupt microbial balance. If raccoons or skunks become a problem, secure your bin with a latch or weight. Metal bins or those with locking lids are best for high-wildlife areas.

Use Compost to Enhance Seattle’s Native Soil

Seattle’s soil is often heavy clay or sandy loam, both of which benefit from compost. Clay soils become more porous; sandy soils retain more water and nutrients. Adding compost improves structure, reduces erosion, and supports beneficial fungi and earthworms—key to healthy Pacific Northwest gardens.

Compost in All Seasons

Don’t let winter stop you. While decomposition slows, you can still collect scraps and layer them into your bin. In fact, a well-insulated pile can generate internal heat even in freezing temperatures. Cover your bin with a tarp during heavy rain to prevent leaching. In spring, turn the pile vigorously to reactivate microbes.

Engage with Your Community

Seattle has a vibrant network of community gardens and composting workshops. Join a local group like the Seattle Tilth Alliance or attend free composting classes offered by SPU. Sharing tips, excess compost, or even a shared bin with neighbors fosters resilience and knowledge exchange.

Track Your Impact

Every pound of food waste you compost keeps methane—a potent greenhouse gas—from entering the atmosphere. The average Seattle household composts 300–500 pounds of organic waste annually. Consider keeping a simple log: “Composted 15 lbs this week.” Over time, you’ll see your environmental contribution grow.

Tools and Resources

Essential Tools for Seattle Composters

• Compost bin: Choose from SPU’s discounted models or build your own from reclaimed wood.
• Pitchfork or compost aerator: Makes turning easier and less labor-intensive.
• Moisture meter (optional): Helps maintain ideal dampness levels.
• Shredder or paper cutter: For breaking down cardboard and paper into fine browns.
• Storage container for kitchen scraps: A countertop bin with a charcoal filter reduces odors indoors.
• Screen or sifter: For separating finished compost from unfinished material.

Seattle-Specific Resources

• Seattle Public Utilities (SPU) Composting Program: Offers free workshops, discounted bins, and downloadable guides. Visit seattle.gov/utilities/composting.
• Seattle Tilth Alliance: Provides hands-on gardening and composting classes, especially for urban residents. Their “Compost 101” course is highly recommended.
• King County Master Composter Program: Trains volunteers to educate their communities. Many graduates offer free home consultations.
• Seattle Farmers Markets: Many vendors sell locally made compost, worm castings, and compost bins. Great place to network with experienced gardeners.
• Nextdoor and Facebook Groups: Search “Seattle Composting” or “Seattle Gardeners” for local advice, free materials, or bin swaps.

Recommended Products for Seattle Conditions

• FCMP Outdoor IM4000 Tumbling Composter: Double-chamber, rodent-resistant, and easy to turn—ideal for small yards.
• Worm Factory 360: Stackable worm bin for apartment dwellers or shaded patios.
• Dr. Earth Organic Compost Starter: Adds beneficial microbes to jumpstart decomposition in cool soils.
• Green Johanna Compost Bin: Insulated, airtight, and designed for colder climates—perfect for Seattle winters.

Free Printable Guides

Download and print these from SPU’s website:

• “Composting at Home in Seattle” PDF – Illustrated guide to materials, bins, and troubleshooting.
• “What Can I Compost?” Poster – Hang it near your kitchen sink as a quick reference.
• Seasonal Composting Calendar – Monthly tips for managing your pile through rain, snow, and sun.

Real Examples

Example 1: The Ballard Townhouse Composter

Anna, a 32-year-old teacher in Ballard, lives in a townhouse with a 150-square-foot backyard. She started composting after attending an SPU workshop. She chose a 30-gallon plastic tumbler bin and placed it under her back deck for shade and protection from rain. She collects coffee grounds from her workplace and scraps from her meals in a countertop bin with a carbon filter. Every weekend, she adds browns—shredded mail and newspaper—and turns the tumbler. Within 3 months, she harvested rich compost for her herb garden. “I used to throw away 10 bags of trash a month. Now I only fill one. And my basil has never been healthier,” she says.

Example 2: The Capitol Hill Apartment Vermicomposter

James, a software engineer, lives in a high-rise with no outdoor space. He bought a Worm Factory 360 and placed it under his kitchen sink. He feeds his worms fruit peels, tea bags, and crushed eggshells. He avoids citrus and onions. Every 2 months, he harvests worm castings and uses them in his indoor plants. He shares tips with his building’s green committee and now has three neighbors composting too. “It’s quiet, odorless, and I feel like I’m doing something real for the planet,” he says.

Example 3: The West Seattle Family Garden

The Rodriguez family in West Seattle has a 5,000-square-foot yard with fruit trees, vegetables, and a lawn. They built a three-bin wooden system using reclaimed pallets. One bin is for active composting, one for curing, and one for storage. They compost all plant waste, leaves, and even paper towels. Their compost feeds their entire garden and is donated to the local community garden. They’ve reduced their trash pickup from weekly to biweekly. “We used to buy soil conditioner. Now we make our own—and it’s better,” says Maria Rodriguez.

Example 4: The Rainier Valley Community Compost

In Rainier Valley, a group of six households created a shared compost bin in a community garden. Each family contributes scraps and browns, and they rotate weekly turning duties. The bin is enclosed with a lock to deter raccoons. They hold monthly “compost potlucks,” where neighbors bring finished compost and recipes using garden produce. The project has become a social hub and a model for other neighborhoods.

FAQs

Can I compost meat and dairy in my backyard in Seattle?

No. While Seattle’s curbside organics program accepts meat, dairy, and cooked food, backyard compost piles rarely reach the high temperatures needed to safely break down these materials. Doing so can attract raccoons, rats, and other wildlife. Stick to plant-based scraps in your backyard system.

How long does compost take to make in Seattle’s climate?

Typically 2–6 months. In spring and summer, with regular turning, compost can be ready in 2–3 months. In fall and winter, it may take 4–6 months or longer. Patience is key—slow compost is often richer and more stable.

Do I need to add compost activators or starter?

Not necessarily. Your existing soil contains billions of microbes that will naturally colonize your pile. However, if your pile is slow or smells bad, a commercial activator or a handful of finished compost can jumpstart decomposition.

What should I do if my compost smells bad?

A foul odor usually means your pile is too wet or has too many greens. Add dry browns (shredded paper, leaves, or cardboard), turn the pile to introduce air, and ensure it’s not sitting in standing water. Covering it during heavy rain can help.

Can I compost during Seattle’s rainy season?

Yes—rain is helpful, but too much can drown your pile. Use a bin with a lid or cover it with a tarp during prolonged storms. Make sure your bin has drainage holes. If the pile becomes soggy, mix in extra browns.

Is composting legal in Seattle?

Yes. Seattle encourages backyard composting and even offers incentives. There are no city ordinances against it, as long as you manage it responsibly to avoid odors and pests.

Can I compost pet waste?

No. Dog and cat waste can contain harmful parasites like roundworms and toxoplasmosis, which are not killed in home compost piles. Dispose of pet waste in the trash or use a dedicated pet waste composter (separate from your garden compost).

How do I know when my compost is ready?

Finished compost looks dark, crumbly, and smells like rich forest soil. You shouldn’t be able to recognize original materials (like banana peels or leaves). If it’s still warm or has a sour smell, it needs more time.

Can I use compost in potted plants?

Absolutely. Mix one part compost with two parts potting soil for a nutrient-rich blend. Avoid using 100% compost—it can retain too much moisture and compact.

What if my neighbors complain about my compost?

Ensure your pile is well-managed: covered, turned regularly, and free of odors. If concerns persist, consider upgrading to a sealed bin or sharing your compost with them. Many neighbors are surprised to learn how little odor a properly maintained pile produces.

Conclusion

Starting a backyard composting system in Seattle isn’t just a practical way to reduce waste—it’s a meaningful act of environmental stewardship that connects you to the land, your community, and the natural cycles of life and decay. With its temperate climate, strong municipal support, and culture of sustainability, Seattle is one of the best cities in the U.S. to begin composting. Whether you’re using a simple pile, a sleek tumbler, or a worm bin on your balcony, every scrap you compost keeps methane out of the atmosphere and feeds the soil that grows your food, flowers, and forests.

The journey begins with one banana peel, one coffee ground, one handful of leaves. Over time, those small actions accumulate into something transformative: richer soil, cleaner air, and a deeper relationship with the environment around you. You don’t need to be a gardener or an expert to start—just curious, consistent, and willing to learn.

Use the tools, follow the steps, and tap into Seattle’s wealth of resources. Join a workshop, share your compost with a neighbor, or simply watch your pile transform over the seasons. In doing so, you’re not just making dirt—you’re building a more resilient, regenerative future, one backyard at a time.