How to Compost Indoors for a Sustainable Garden

Composting is an affordable way to create additional nourishment for your plants and reduce your general household waste. Luckily, even if you don’t have a yard or live in a small apartment, you can still take up the practice and reap its benefits indoors. 

If you’re just starting your composting journey, the experts from Fantastic Gardeners have provided a helpful guide for you to get a sound start.

Indoor Composting Benefits

One of the most significant advantages of indoor composting is that it thrives all year round from temperatures as low as 4 to 26 degrees Celsius. In contrast, outdoor composting bins and piles need to be specially protected from direct sunlight and heavy rainfall and kept warm if the temperature falls below 4 degrees Celsius. However, even if that’s taken care of, an outdoor compost pile isn’t as productive during winter because the waste matter decomposes slower in cold weather. 

Besides that, indoor composting is suitable if you have limited living space. You can pretty much store it in any dark and dry area, such as a basement, closet or even under the kitchen sink. On the other hand, outdoor composting requires more space. 

Composting Tools and Materials

Making an indoor compost bin is quite simple. You’ll need the following tools and materials:

• Electric drill; 
• Glue gun;
• Plastic bin, 10 or 20 litres with a tight-fitting lid;
• Plastic or rubber tray wider and longer than the bin’s base to prevent potential leaks. Make sure it also has walls at least 5 centimetres in height, so no liquid spills out of it; 
• Fine mesh filters.

A proper compost pile needs plenty of oxygen for the matter to decompose properly, so start by drilling a grid of small holes evenly spaced apart on the plastic bin’s lid, walls and bottom. Afterwards, use a glue gun to glue the fine mesh filters to the inside of the bin. This will prevent it from becoming a hangout spot for cockroaches and fruit flies.

The best options for indoor composting bins are lidded plastic storage containers, plastic or metal garbage cans or wooden crates. Whatever you choose, its size should be considered in your final decision. The bin should be able to fit inside the space you intend to store it but still be large enough to hold more than the weekly volume of matter you plan to compost.

Composting Basics

A successful compost consists of two main ingredients: carbon-rich browns and nitrogen-rich greens. The carbon-rich browns include matter like dried leaves, cotton and wool rags, cardboard and paper. In contrast, nitrogen-rich greens are things like fresh leaves, green grass clippings produced during your regular garden clearance activities, and veggie and fruit scraps left from the cooking process.

It’s recommended to start your compost pile with a thick layer of carbon-rich browns around 12 to 13 centimetres deep. It’ll help absorb all the moisture from the pile on top, keep everything well-aerated and lower the possibility of stagnation.

Besides that, knowing the correct ratio between browns and greens is essential to get the most out of home composting. Scientists say that to get sweet-smelling compost quickly. You should maintain a balance of 3 parts carbon to 1 part nitrogen.

To start your compost bin:

• Fill up 3/4 of the container with brown matter and gently toss it around. 
• Sprinkle an even layer of 1 cup of garden soil on top of the brown matter. 
• Gather your scraps in a separate container throughout the week. Once a week, bury them in the brown matter and soil mixture. Always chop or tear them prior to composting because smaller items break down quicker.
• Turn the contents of your compost bin with a fork once a week to allow an adequate oxygen supply.

Optionally, top the soil layer with 400 grams of worms for every 1,5 kg of organic waste your household generates weekly. They can eat half of their weight in waste daily. However, avoid dew worms, which die quickly, or invasive species. If you decide to add worms to your compost, replace the lid of the container to prevent them from escaping until you’re ready to compost. Additionally, if you add worms to your compost, there’s no need to turn the matter manually because they aerate the compost naturally as they tunnel through it. 

Keep in mind that it may take 2 to 4 months or even longer for all the contents of your compost bin to turn into a soil-like compost. Once that happens, remove it and use it as you desire. Add new base, soil and worms (optionally) and resume composting your food scraps.  

What You Can and Can’t Compost

Things you can throw into your indoor compost bin include:

• Clean cardboard and paper devoid of plastic, such as brown paper bags, cereal boxes, paper towels and shredded newspapers;
• Cotton and wool rags;
• Coffee filters;
• Crushed eggshells;
• Fruits and veggie scraps;
• Fallen houseplant leaves;
• Teabags and tea leaves;
• Nut shells;
• Burnt matches;
• Ash from the fireplace;
• Small twigs, hay straw and wood chips.

Things not to compost include:

• Meats, egg whites and yolks, fish or other poultry scraps. They will make your compost bin smell bad and attract pests. 
• Dairy products, fats, lard, grease and oil. Similarly, they’ll make your compost smell bad and attract pests.
• Pet excrements. They may introduce parasites and germs to the compost.

Compost Uses

Homemade compost can be spread over potting soil and used as mulch for your indoor and outdoor plants. Combining 1 part potting soil with 2 parts compost makes a great, nutrient-rich soil which can serve as the perfect base for starting a vegetable garden.

When collecting the compost from the bin, you can also use any liquid collected in the tray below it. Dilute it with 10 parts water and fill it in a spray bottle. It will make a perfect spray for nourishing houseplants.

Compost Odour Issues

It’s important to note that converting waste into compost shouldn’t produce any unpleasant odours other than a mild, earthy scent. If you notice an issue with the compost smell, it may be because of the following issues:

• High moisture level in the bin. You can solve that by adding more brown matter to increase the compost dryness. 
• Too much food in the bin. In that case, don’t add any more food scraps until the present waste is decomposed. 
• Lack of oxygen. Add more holes in the bin and aerate the compost more frequently. You can also place a brink or another object between the container and the tray to elevate it and improve the airflow. 

Remember also never to leave the compost bin exposed to air because it can attract fruit flies. 

Final Words

Even if you only have limited space, you can still start composting and be successful. While the overall process can often be messy and long, it’s a rewarding and environmentally-friendly practice to manage household waste. After all, every person’s actions matter when it comes to caring for the planet, and you can only leave a positive impact.