Boosting Winter Composting Efficiency with Coffee Grounds and Tea Leaves

winter composting, composting tips

Article written by T. Hawkins

“The amount of compostable material in Australians' garbage bins has decreased by approximately 5% over the past two years”, the Australian Museum reveals.

Although composting inevitably slows down in the winter, that doesn't mean you should go back to throwing food scraps in the trash until the sun comes out again. You just need to take a little extra care to keep your compost insulated, active, and thriving during the colder weather. In particular, the addition of nitrogen-rich coffee grounds and tea leaves can give your winter composting a helpful boost.

Thanks to their excellent nitrogen:carbon ratio and slightly-acidic pH, these two special ingredients can speed up the composting process and get your soil healthy and ready for spring planting.

Near-perfect carbon:nitrogen ratio

Coffee grounds and tea leaves can function as nitrogen-rich “green” materials in your winter compost heap. Both these scraps have a carbon:nitrogen ratio of roughly 20:1, which is close to the perfect ratio needed for healthy composting (25:1). But, it’s also important to still balance out your winter compost with brown materials (like eggshells, leaves, and straw) to provide enough carbon for the decomposition process.

The nitrogen provided generates the heat that the microorganisms need to continue doing their job over winter: successfully breaking down the organic matter into soil-enriching minerals. These two special ingredients also make composting more convenient, as while it’s not always easy to find green materials like leaves and grass clippings during the winter, you’ll always have coffee grounds and tea leaves on hand.

Slightly acidic pH = faster decomposition

Coffee grounds and tea leaves are also slightly acidic, which can further help speed up the winter decomposition process. Specifically, coffee grounds have a pH of roughly 6.5-6.8, near neutral (7), whereas tea leaves have a pH of around 5-6. Since fungi and bacteria thrive in these kinds of slightly acidic conditions, this can help them get to work and break down the organic matter faster despite the colder weather.

And, once spring finally rolls around, you’ll have amazing, mature compost ready for garden use. With this nutrient-rich compost, you can prioritise the health and longevity of your plants and shrubs, and give them the soil conditions they need to thrive. In particular, the average shrub lifespan is typically between ten to fifteen years, but they can last even longer with good care.

One key way to keep plants at their healthiest is to use fertiliser in addition to compost. Compost works to feed the soil, whereas it’s the job of the fertiliser to feed the plants. Both can play a key role in creating a healthy, thriving garden.

How to compost tea leaves and coffee grounds

After steeping your tea or brewing your coffee, simply remove the leftover loose leaves or grounds from your pot, and place them on a plate or bowl to cool. Once cool, you can then throw them into your compost bin. Note: be careful not to go overboard with the amount of leaves or grounds you add to your compost. Large amounts can easily become compacted, which means composting will slow down, and potentially even start to smell. Moderation and balance with carbon-rich “brown” materials is key.

Don’t compost tea bags

Although tea leaves are great for your compost and soil, tea bags, however, aren’t. Tea bags usually contain thermoplastic like polypropylene that acts as a heat seal, so they don’t fall apart in your mug when you’re brewing a cuppa. As most thermoplastics aren’t biodegradable, that means they won’t break down in your compost heap. And even though most tea brands are now switching (or have already switched) to plant-based polylactic acid (PLA), in most cases, this material can still take hundreds of years to break down. So, it’s best to stick to tea leaves for your compost bin, and throw your tea bags in your food waste bin instead.

Coffee grounds and tea leaves can boost your compost during the winter months. By regularly adding these nitrogen-rich scraps to your compost heap, you’ll be rewarded with healthy compost that can help ready your garden for spring planting.

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About David Gravina

Founder of Revolution Apps, into social change and worms.
  • Sydney, Australia