Want to use up your organic waste, but worried about your house smelling like decomposition? Don't worry: with good composting practices With the right container, it's possible to create top-quality compost without unpleasant odors, even in a small apartment.
In a context of sustainable living And in commitment to the 2030 Agenda (Goal 12 on responsible consumption and production), every gesture counts. The UN warns that nearly a third of the food produced in the world ends up in the trash: that's millions of tons and a huge amount of money wasted. Turning those scraps into home compost It reduces waste, saves money, and returns nutrients to the soil without chemicals.
What is compost and why make it at home?
Compost is a organic fertilizer which is obtained when microorganisms such as fungi and bacteria transform plant and kitchen scraps into a dark, loose, earthy-smelling substance. There are also variants produced by earthworms (vermicompost) and an airless fermentation format (Bokashi) that stands out for its extremely low level of odors.
In addition to improving soil structure, compost provides essential nutrients (N, P, K and micronutrients), increases water retention and activates beneficial microbial life. It is estimated that for every 100 kg of organic waste you can obtain up to 30 kg of fertilizer usable in pots, gardens and planters.
Compost can be presented in the form solid or liquidThe solid form is most commonly used for mixing with soil or as mulch; the liquid form (compost tea or leachate in specific systems) allows for a very convenient application through irrigation or spraying.
Beyond the garden, composting at home is a clear gesture of circular economy: You reduce the waste we send to landfills (and the methane it generates) and achieve autonomy from commercial fertilizers.
If you're worried about smells, there are tried and tested techniques and specific containers that make the process possible. clean and discreeteven indoors.
Choosing and preparing the composting container
You can make a homemade composter or buy one. home composter Ready to use. Indoors, it's best to prioritize well-designed equipment that controls ventilation, drainage, and, above all, odors.
If your priority is saving space, there are compact vermicomposters Designed for apartments. They work the same way: cardboard bed, finely chopped organic waste, and the worms working their magic at a steady pace.
The Bokashi method, on the other hand, ferments the waste without oxygen using... specific microorganismsIt's a very clean system: being anaerobic, it doesn't generate putrefaction, so there are almost no odors or insects. The resulting material is then buried to complete the transformation, and the liquid (Bokashi juice) serves as... diluted fertilizer and, undiluted, as a domestic unblocker in pipes.
There are indoor Bokashi cubes made with recycled materialsThey are compact (approximately 35 × 24 × 25,7 cm), perfect for fitting under sinks or in discreet corners. Some include activator powder and a tap for collecting the leachate.
In classic aerobic composting (without worms), an airtight bin is not recommended: the microorganisms need oxygenTherefore, there are ventilated bins with lids and activated carbon filters to trap odors and mosquitoes. In the premium segment, automatic systems have emerged that remove and ventilate They work on their own and promise results in a few hours, designed for modern kitchens.
What materials to use and which to avoid
The key to success is combining “greens” (nitrogen) y “browns” (carbon) in a suitable proportion to accelerate decomposition and prevent bad odors.
Green materials (rich in nitrogen)
- remains of fruits and vegetables raw, finely chopped.
- Pits of café y tea bags (without staples).
- Eggshells crushed.
- Grass freshly cut and green pruning remains.
- Flores withered.
These residues are moist and “energetic” for microbes; combined with dry materials They balance moisture and structure.
Brown materials (rich in carbon)
- Leaves drystraw, hay.
- Thin branches, splinters and sawdust of untreated wood.
- Paper and cardboard without inks or lamination, chopped into pieces.
- shells of nuts.
Browns provide structure and aeration, helping the flow of oxygen I reached the whole pile.
Recommended proportion
Maintain a relationship of 2-3 parts brown for each part of greens. This translates into more generous dry layers and fine moisture control.
What you shouldn't add
- Meat, fish and dairyThey attract pests and cause bad smells.
- Oils and fatsThey form impermeable layers that slow down decomposition.
- Pet droppingsThey can carry pathogens.
- sick plants or with pests, and weeds with viable seeds.
- Treated wood, paints or remains with chemicals.
If you're looking for animal-based fertilizers, use products specifically treated for agriculture (e.g., commercial guano), not unprocessed domestic feces.
How to make compost without odors: step by step
The key to odorless composting is good management of the moisture’s most emblematic landmarks, the oxygen and the balance of materials. From there, you can choose vermicomposting (with worms) or the Bokashi method.
Vermicomposting
- Prepare one cardboard bed or consistent paper at the bottom.
- Add another layer of shredded cardboard, 4-5 cm thick, and moisten it with a spray bottle.
- Enter the earthworms along with the land of its habitat.
- Place the organic remains chopped up and cover with another layer of paper/cardboard.
The humidity should resemble a wrung-out spongeIf it drips, there is too much water. As they work, you will collect humus and the valuable “worm tea"From the bottom if your equipment has a tap."
If you have a garden, a vermicomposter like flowerbed or border It is installed on the site itself to transform kitchen waste on site.
Bokashi Method
- Compact the waste inside the cube to expel the air.
- sprinkle fermenting microorganisms (activator) on each contribution.
- Repeat layers until full and close the container.
- Let it ferment 14 days unopened.
- Collect the liquid and dilute it to 100:1 for use as fertilizer; the fermented solid is buried or mixed with compost.
Bokashi is perfect for floors because fermentation prevents... putrefaction and the appearance of small flies.
Humidity control and ventilation
For aerobic compost, stir the contents every 7-10 days Using a fork or stick, break up compacted areas. Adjust the moisture: add more brown if there is excess water or spray if it is dry.
temperature and ventilation
The process generates heat: that's a good sign. A well-ventilated container with carbon filters It helps manage odors in the kitchen. Outdoors, simply ensure ventilation and drainage.
If it smells bad, fix it.
Bad smells usually come from excess waste (They rot before decomposing) or due to too much moisture. Add dry materials, ventilate, and check that you haven't included any prohibited items.
Maturation time and signs that it is ready
Depending on the climate, size of the pieces, mixture and aeration, the process takes between 2 and 6 monthsYou'll know the compost is mature when it has a dark brown color, an earthy texture, and It smells like damp earth., without recognizable features of the original remains.
If you detect a rancid smell, there is probably a lack of oxygen or too much of it. greenCorrect with browning and turning. In Bokashi, remember that the cube phase is fermentation; maturation is completed after burying it or mixing it with compost.
Typical mistakes and how to avoid them
The most common mistake is to unbalance the mix: too many green They generate moisture and odor; too many brown ones slow down decomposition.
- Uncontrolled humidityAdjust to "wrung-out sponge". Drier, sprays; wetter, adds browns.
- Lack of oxygenStir regularly to avoid compacted areas and anaerobic processes.
- Inadequate materials: no meat, dairy, oils, chemicals or pet feces.
- Pieces too large: chop or grind; small fragments transform faster.
With these corrections, your compost will stay odors to keep at bay and will progress at a good pace.
How to use compost: sifting, application and dosage
Pre-screening
Before using it, put the compost through a sieve or screen Tilted to separate coarse pieces, twigs, or stones. The fine pieces return to the garden; the coarse pieces go back to the pile to continue ripening.
When and how to apply
Tras 6-12 monthsFresh compost can now be used as a mild fertilizer. Note: its exact nutrient content depends on what you added, so use it sparingly.
- In the gardenDistribute 2-5 cm on the surface and mix with the first 10-15 cm of the ground.
- in pots: combine 1 part compost to 3 parts commercial substrate to avoid saturation.
- As mulch: spread 2-5 cm around, leaving an uncovered ring next to the stem.
If you normally fertilize with commercial products, by incorporating compost you can reduce dose of other fertilizers around 50% (depending on how "greedy" the plant is).
Guideline doses
An easy guideline is to apply between 3 and 4 liters of compost per square meter (approx. one shovelful) in garden soils. If you use it as a structural conditioner, let it mature for at least a year: it will have fewer nutrients but more stable humus, which improves the soil in the long term.
Compost tea
Compost tea is a liquid fertilizer Rich in beneficial microorganisms. Use chlorine-free water (distilled, rainwater, or tap water left to stand for 24 hours) to avoid harming these organisms.
- Put 1 part compost into a cloth bag.
- Submerge it in 10 parts of chlorine-free water for 24-48 h.
- Stir occasionally and use it as soon as possible for watering or spraying.
In vermicomposters with a tap, the worm tea It is collected directly and applied diluted according to the manufacturer's recommendation.
Urban composting, recycling and odor management
The separation of organic waste in Spain has been strengthened with the brown containerMandatory since 2024 in municipalities and autonomous communities. You can take your remains there or opt for a home composter to close the cycle at home.
For indoors, choose ventilated cubes with carbon filters that trap odors and keep insects away. In automatic systems, removal and assisted ventilation simplify daily maintenance.
If you choose Bokashi, you minimize odors thanks to the anaerobic fermentationThe resulting liquid, diluted, is an excellent fertilizer; undiluted, it functions as drain cleaner punctual due to its acidic and microbial activity.
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Transforming your organic waste into black gold without worrying about odors is an act of everyday magic. The key is balance: a suitable container, a good dose of patience, and that perfect balance between wet (green materials) and dry (brown materials).
Whichever method you choose Bokashi or the wonderful world of VermicompostYou will be turning what was once "waste" into pure life for your gardenIt's a cycle that connects you with nature: you keep your plants healthy, the soil fertile, and most importantly, your home free of nuisances and with a clearer conscience!
