Home Composting Experiment — Frequently Asked Questions

Q1: Can compost really be made in two weeks?

Fully mature compost cannot usually be produced within two weeks, but you will be able to observe clear signs of decomposition. Fruit peels may darken, vegetable leaves may soften and collapse, the overall volume may decrease, and the smell may begin to change. A two-week period is therefore best understood as a rapid composting observation experiment. The resulting material is more accurately described as “pre-compost” rather than finished compost.

Q2: Can the compost be used directly on plants after one month?

It is not recommended to apply large amounts of one-month-old compost directly to plants. At this stage, the material may still be only partially decomposed. Ideally, allow it to mature for another two to four weeks. When using it, mix the compost thoroughly with regular soil rather than planting directly into pure compost, as unfinished decomposition may affect plant roots.

Q3: Why should dry material be added every time food scraps are added?

Shenzhen summers are hot and humid, and kitchen scraps naturally contain a large amount of moisture. If the bin contains only fruit peels and vegetable scraps, it can quickly become wet, smelly, and attractive to insects. Dry materials such as shredded cardboard, coconut coir, and dry leaves help absorb excess moisture, reduce odours, create air pockets, and provide an essential source of carbon. A simple guideline is to use one part food scraps to two or three parts dry material.

Q4: Why does the compost smell bad?

Strong unpleasant odours are usually caused by one of three problems: too many food scraps, too much moisture, or not enough air. When an odour appears, immediately add shredded cardboard, coconut coir, or dry leaves, and turn the material once. Stop adding new food scraps for two to three days and make sure the compost bin has sufficient ventilation holes.

Q5: What should I do if small flies appear?

A small number of flies is common during hot summer weather. Every new addition of food scraps should be completely covered with dry material, and fruit peels should never be left exposed on the surface. Add a final layer of dry leaves or coconut coir and keep the lid closed. Avoid adding large quantities of very sweet or juicy fruit. When such fruit is added, cut it into small pieces and bury it well inside the compost.

Q6: Can watermelon rind be composted?

Yes, watermelon rind can be added, but it must be cut into small pieces and used only in limited quantities. Watermelon rind contains a very high level of moisture, so it should always be combined with plenty of shredded cardboard, coconut coir, or dry leaves. Without enough dry material, the compost may become overly wet, acidic, and unpleasant-smelling.

Q7: Can cooked leftovers be added?

A small amount of plain, unseasoned rice may be added, but leftovers containing oil, salt, sauces, or strong seasonings are not recommended. Stir-fried dishes, hotpot leftovers, soup, meat, and greasy foods are unsuitable for this household experiment because they are more likely to produce odours and attract pests.

Q8: Can eggshells be added?

Yes, eggshells can be included. Before adding them, wash them thoroughly, allow them to dry completely, and crush them into small pieces. Eggshells will not visibly disappear within two weeks, but they are useful observation materials and can gradually become part of the soil cycle over a longer period.

Q9: Where should the compost bin be placed?

Place the compost bin in a shaded area of the balcony or in a well-ventilated corner. Protect it from direct sunlight and heavy rain. It should not be kept inside a closed kitchen cupboard. Because Shenzhen summers are very hot, a partially shaded and ventilated location will provide more stable composting conditions than direct sun exposure.

Q10: Does the compost need to be turned every day?

No. During a two-week experiment, turning the compost once every two or three days is sufficient. Turning it too frequently may disturb the decomposition process, while never turning it may create oxygen-poor conditions. A useful rule to remember is: when you notice an unpleasant smell, add dry material first and then turn the compost.

Q11: Why should food scraps be cut into small pieces?

Smaller pieces have a larger surface area exposed to air and microorganisms, allowing them to decompose more quickly. Fruit peels and vegetable scraps should ideally be cut into pieces of approximately one to two centimetres. Large pieces, especially watermelon rind, banana peel, and tough vegetable skins, should not be placed in the bin whole.

Q12: What makes this composting experiment successful?

Success does not necessarily mean producing dark, fully mature compost immediately. The purpose is to observe and understand the transformation taking place: the volume of the food waste decreases, the materials become darker, and the smell gradually changes from that of fresh food to something closer to soil. The most important outcome is seeing that everyday waste can begin to be transformed through a natural process.

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