If you live in Oregon, Washington, or anywhere in the Pacific Northwest, you already know: moss doesn’t just visit your lawn — it moves in, unpacks, and starts redecorating. The combination of heavy rainfall, mild winters, acidic soil, and shade from towering evergreens creates a moss paradise. And what’s paradise for moss is a nightmare for grass.

The good news? You can fight back. The key is using the right products at the right time, paired with cultural practices that tilt conditions back in favor of turf. Here’s a breakdown of the best moss control products for Northwest lawns in 2026, based on effectiveness, ease of use, and value.

Understanding Why Moss Takes Over

Before you buy anything, it helps to understand what you’re dealing with. Moss thrives where grass struggles:

  • Acidic soil (pH below 6.0)
  • Compacted or poorly drained soil
  • Heavy shade
  • Excessive moisture
  • Thin or weak turf

Killing moss without fixing the underlying conditions is like mopping the floor while the faucet’s still running. The best approach combines a moss killer with soil amendments and overseeding to fill in bare spots before moss returns.

Best Iron-Based Moss Killers

Iron-based products are the gold standard for moss control. They’re effective, relatively safe for grass, and they even green up your lawn in the process.

1. Lilly Miller Moss Out! Lawn Granules

Lilly Miller Moss Out! Lawn Granules on Amazon

This is the go-to moss killer for Northwest homeowners, and for good reason. The active ingredient is ferrous sulfate monohydrate (10%), which blackens and kills moss on contact within hours. You’ll see results in 24-48 hours — dead moss turns black and can be raked out.

  • Coverage: 5,000 sq ft per 20 lb bag
  • Application: Broadcast spreader, apply when moss is actively growing (fall through spring)
  • Bonus: Adds iron to the soil, which greens up grass
  • Price range: $15-20 per bag

Best for: Homeowners who want fast, visible results and don’t mind raking out dead moss afterward.

2. Scotts MossEX

Scotts MossEX on Amazon

Scotts MossEX uses a similar iron-based formula but adds a nutrient package to help grass fill in where moss was. It’s a two-in-one approach: kill the moss and feed the lawn simultaneously. Results show within hours, and the granular format makes application easy with any broadcast spreader.

  • Coverage: 5,000 sq ft per 18.37 lb bag
  • Application: Apply when temps are above 40°F and moss is actively growing
  • Contains: Iron plus lawn fertilizer nutrients
  • Price range: $20-25 per bag

Best for: Folks who want moss control and fertilization in a single pass.

3. Bonide MossMax Lawn Granules

Bonide MossMax on Amazon

Bonide’s offering uses ferrous sulfate and works similarly to Lilly Miller, but some users report it spreads more evenly through a rotary spreader. It’s a solid alternative if Lilly Miller is out of stock — which happens every February in the Northwest, predictably.

  • Coverage: 5,000 sq ft per 20 lb bag
  • Application: Broadcast spreader, water in lightly after application
  • Price range: $18-22 per bag

Best for: A reliable backup option with consistent results.

Best Liquid Moss Killers

If you prefer spray application for targeted treatment, liquid products give you more control over where the product goes.

4. BioAdvanced 2-in-1 Moss and Algae Killer

BioAdvanced Moss and Algae Killer on Amazon

This ready-to-spray formula attaches to your garden hose and lets you treat specific mossy patches without broadcasting product across the entire lawn. It works on moss, algae, and lichens — all common in the Northwest’s damp climate.

  • Coverage: Up to 500 sq ft per bottle (concentrated areas)
  • Application: Hose-end sprayer, apply on a dry day with no rain expected for 24 hours
  • Results: Visible within 3-5 hours
  • Price range: $12-16 per bottle

Best for: Spot-treating mossy patches in walkways, shady corners, or small lawn areas.

5. Safer Brand Moss and Algae Killer Concentrate

Safer Brand Moss Killer on Amazon

For the eco-conscious Northwest homeowner (and there are many of you), Safer Brand uses potassium salts of fatty acids — essentially a soap-based formula that desiccates moss. It’s OMRI-listed for organic use, which matters if you’re maintaining an organic lawn or have concerns about iron staining on nearby hardscapes.

  • Coverage: Makes up to 3 gallons of spray
  • Application: Pump sprayer or hose-end sprayer
  • Active ingredient: Potassium salts of fatty acids
  • Price range: $14-18 per concentrate bottle

Best for: Organic lawn care enthusiasts or anyone worried about iron staining on concrete.

Soil Amendments for Long-Term Prevention

Killing moss is step one. Preventing it from coming back is the real game. These soil amendments address the root causes.

6. Espoma Organic Garden Lime

Espoma Garden Lime on Amazon

Most Northwest soils run acidic — often pH 5.0 to 5.5. Grass prefers 6.0 to 7.0. Lime raises your soil pH, which makes conditions less hospitable for moss and more favorable for grass. Espoma’s pelletized lime is easy to spread and won’t create dust clouds like powdered lime.

  • Coverage: 5,000 sq ft per 36 lb bag
  • Application: Broadcast spreader, apply in fall or early spring
  • How often: Test soil pH annually; reapply as needed (usually every 1-2 years in the NW)
  • Price range: $8-12 per bag

Best for: Every Northwest homeowner. Seriously. If you haven’t limed your lawn, start here.

7. Jonathan Green Mag-I-Cal Plus for Lawns in Acidic Soil

Jonathan Green Mag-I-Cal Plus on Amazon

This is lime on steroids. Mag-I-Cal Plus raises pH faster than traditional lime and includes calcium and sulfur to improve soil structure. It’s more expensive per bag but covers more ground and works faster — you’ll see pH changes in weeks rather than months.

  • Coverage: 5,000 sq ft per 18 lb bag
  • Application: Broadcast spreader
  • Speed: Raises pH noticeably within 2-4 weeks
  • Price range: $22-28 per bag

Best for: Homeowners with very acidic soil (pH below 5.5) who want faster results.

Overseeding to Fill the Gaps

Dead moss leaves bare soil. Bare soil invites more moss. Break the cycle by overseeding immediately after moss removal.

8. Scotts PNW Grass Seed Mix (or equivalent shade-tolerant mix)

Scotts Pacific Northwest Grass Seed on Amazon

After raking out dead moss, overseed with a mix designed for Northwest conditions. Look for fine fescue blends (creeping red fescue, chewings fescue) mixed with perennial ryegrass. These grasses tolerate shade, acidic soil, and wet conditions better than Kentucky Bluegrass.

  • Coverage: Varies by product; check bag rates
  • Application: Rake dead moss, loosen soil surface, broadcast seed, top-dress with compost, keep moist
  • Timing: Best in September-October, but early spring (March-April) works too
  • Price range: $25-40 per 7 lb bag

Best for: Filling in bare patches left by dead moss to prevent re-infestation.

The Complete Northwest Moss Battle Plan

Here’s how to put it all together for February through April:

  1. Now (February-March): Apply an iron-based moss killer (Lilly Miller or Scotts MossEX). Wait 2-3 weeks for moss to die completely.
  2. After moss dies: Rake out dead moss thoroughly. This is the most labor-intensive step, but skip it and you’ll smother the grass underneath.
  3. Apply lime (Espoma or Mag-I-Cal Plus) to raise soil pH. Get a soil test first if you haven’t tested recently — the same principles apply regardless of region.
  4. Overseed bare spots with a shade-tolerant Northwest grass mix.
  5. Top-dress with compost (¼ inch layer) to improve soil structure and moisture retention.
  6. Aerate in fall to reduce compaction — another moss-friendly condition. If you’re not sure when to dethatch or aerate, get that sorted before fall.

What About Dish Soap and Baking Soda?

You’ll find plenty of DIY moss killer recipes online using dish soap, baking soda, or vinegar. Do they work? Sort of. Dish soap can desiccate moss temporarily, and baking soda raises pH slightly. But neither is as effective or long-lasting as iron-based products or proper liming. Save the dish soap for dishes.

Final Thoughts

Moss control in the Northwest is an ongoing relationship, not a one-time fix. The climate will always favor moss, so your job is to consistently tip conditions in favor of grass: raise soil pH, reduce compaction, improve drainage, increase sunlight where possible, and keep turf thick and healthy.

The products above are proven performers in the PNW climate. Start with an iron-based killer and lime this spring, overseed aggressively, and you’ll see meaningful improvement by summer.

For a deeper dive into regional lawn care strategies tailored to the Northwest, check out the Lush Lawns Pacific Northwest Edition — it covers everything from moss to mowing height to seasonal fertilization schedules specific to your climate.