How to Compost Lawn Clippings: Turn Mowing Waste Into Garden Gold on the Sunshine Coast

Written By Clay Muston

If you’ve been mowing regularly, you’re sitting on a goldmine — of compost. Lawn clippings are packed with nitrogen, making them an excellent ingredient for rich, garden-ready compost. Whether you're into full-scale permaculture or just want to recycle your green waste, composting clippings the right way can reduce landfill, feed your soil, and improve your garden’s health — all without leaving the Sunshine Coast.



Why Compost Lawn Clippings?

  • It reduces green waste going to landfill

  • It returns nutrients to your soil

  • It improves water retention and structure in your garden beds

  • It’s free and sustainable — no fertiliser required

The Carbon-to-Nitrogen Balance: Geoff Lawton’s Rule + A Practical Shortcut

As permaculture expert Geoff Lawton explains, the ideal composting mix is around 25–30 parts carbon to 1 part nitrogen — by weight. That’s the sweet spot where beneficial microbes thrive and break material down quickly into dark, crumbly compost.

But let’s be real — most of us don’t weigh out our compost ingredients. So here’s a practical volume-based shortcut:

Mix about 3 parts dry brown material (carbon) to 1 part fresh lawn clippings (nitrogen)

wood chip used a carbon source sunshine coast

Woodchips are a great carbon-rich “brown” material that helps balance the nitrogen from lawn clippings in compost. They improve airflow, reduce odour, and support aerobic microbes for faster, healthier decomposition.

Carbon (“Browns”) Includes:

  • Dried leaves and woodchip

  • Shredded cardboard or newspaper

  • Straw or hay

  • Sawdust (in moderation)

Nitrogen (“Greens”) Includes:

  • Fresh lawn clippings

  • Veggie scraps

  • Coffee grounds

  • Fresh garden trimmings

Avoid creating a dense wet pile of just lawn clippings — it’ll go slimy fast. The balance is everything.

Aerobic vs. Anaerobic Bacteria: What the Smell Tells You

Your compost is basically a microscopic farm — and who’s running the show depends on how well you manage air, moisture, and materials.

🟢 Aerobic (Good) Bacteria

  • Thrive with oxygen

  • Break down compost efficiently

  • Create a sweet, earthy smell — like fresh soil

  • Prefer the 25–30:1 carbon-to-nitrogen range

🔴 Anaerobic (Bad) Bacteria

  • Take over in wet, compacted piles with little airflow

  • Produce a sour, rotten, or ammonia-like smell

  • Slow the composting process

  • Can cause mold, slime, and pests

🧠 Smell Test Tip:

If your compost smells bad, it's telling you:

  • There’s too much nitrogen (clippings, food scraps)

  • Not enough airflow or dry material

Fix it fast by mixing in dry carbon sources like leaves or cardboard and fluffing the pile for aeration.

What Not to Compost from the Lawn

  • Lawn clippings treated with weed killers

  • Grass with visible fungal disease

  • Thick wet piles of clippings on their own — they need to be mixed in

Can You Compost Grass Seed Heads?

If your lawn has gone to seed before mowing, you might be wondering whether those seed heads are safe to compost. The answer is: yes, but with caution.

Composting Safely

Grass seeds can survive in a cool or poorly balanced compost pile. If your compost doesn’t heat up to at least 55–65°C (130–150°F), many seeds may remain viable — and later sprout where you don’t want them.

This is where the carbon-to-nitrogen (C:N) ratio becomes critical.

To reach composting temperatures high enough to destroy seeds, your pile needs the right balance of:

  • Nitrogen-rich “greens” like fresh lawn clippings

  • Carbon-rich “browns” like woodchips, dried leaves, or cardboard

The ideal ratio is around 25–30 parts carbon to 1 part nitrogen by weight — or roughly 3 parts browns to 1 part greens by volume for backyard composting.

When that balance is right, aerobic bacteria thrive. These microbes break down materials quickly and generate heat as a by-product of their activity, naturally warming the pile to seed-killing temperatures.

What You Can Do:

  • If your pile is mostly grass, add plenty of browns to avoid a cold, soggy mess

  • Avoid compacting fresh clippings — mix them well to keep oxygen flowing

  • If you’re unsure whether your compost gets hot enough, it’s safest to:

    • Let seed-heavy clippings dry out first

    • Or remove and discard them separately

In Sunshine Coast conditions, a well-built pile with the right mix of ingredients will usually heat up nicely — and take care of any unwanted seeds in the process.

How to Use Finished Lawn Compost

When your compost is:

  • Dark brown or black

  • Crumbly

  • Smells earthy

…you’re good to go. Use it to:

  • Mulch your garden beds

  • Enrich veggie patches

  • Blend into potting mix

  • Top-dress lawn areas

Don’t Want to Compost It Yourself? No Worries.

At Lawn in Order Mowing, we can take the clippings away — or leave them behind if you're building your own compost. We’re all about making yard care easier, whether you're hands-on in the garden or just want it sorted for you.

Clay Muston