Most of us enjoy a bowl of cereal or oatmeal in the mornings before rushing off to work. The high fiber, whole wheat grains, and nutrient enrichment make it a filling and healthy meal. But when you need to rush out and can’t finish or when a box of cereal gets stale, can you toss it in the compost, or will that cause unwanted problems?
What Happens When You Compost Cereal?
Adding cereal to a compost pile can have different effects depending on the condition of the cereal. Some types of cereal will go through the composting process quickly and make rich finished compost. Other conditions of cereal could cause bad odors in the compost heap and attract unwanted pests and wild animals.
It is best to make sure leftover cereal is dry and not still soaked in dairy products. Putting unfinished cereal on paper towels before tossing them into the compost pile can help absorb some of the odor-causing milk. Once the cereal is dry, you can put it in the compost with the rest of your breakfast waste, like eggshells and coffee grounds.
Cereal grains are high in organic matter, and since most of them are grasses have high nitrogen levels like yard waste. It is good to compost cereal grains with wood chips or to grind up stale cereal and mix it with wood ash. Other kitchen waste and organic matter should be added to help it break down faster.
Grains attract rodents and will be easily detected by their strong sense of smell. To keep wild animals from digging up your pile, you can place grass and other compostable materials on top of the cereal grains. The deeper they have been buried under garden waste, the less risk of being found by animals, and some plant materials, like pine needles, can further mask the grain’s scent.
Cereal grains have high nitrogen content and need to be composted with brown organic waste. Using wood chips and organic waste to jump-start the composting process is the best way to release nutrients to plants. Other compostable materials and garden waste can be mixed with grains to help them disperse throughout the pile and not clump together when moisture is added.
| Condition of Cereal | How to Prepare | What it Adds to Compost |
| Wet with Milk | Dry with paper napkins or towels and pour excess milk into the sink | The nutrients and the absorbed fats and sugars can help boost microorganisms in the soil |
| Dry and Stale | Grind into powder | High levels of micronutrients and nitrogen are added to the soil and easily absorbed by plants |
| Soggy and Old | Tossed into compost with other compost materials and mixed together | Reduces food waste and builds water retention and nutrients into the compost |
Wet with Milk
It is a good idea to avoid adding dairy to a compost pile. The fats break down and cause a sticky situation, and the stench will attract pests. Animal waste and pet waste can end up being added to the compost and cause bacterial health risks in future plants and gardens. If there is a bit of waste left over that has milk, you can increase compost temperatures rapidly to kill off any pathogens and avoid long-term odor problems.
You can rinse leftover cereal that has milk on it in water and then let it dry. Adding wet cereal to the compost with plain paper or any piece of paper can help absorb moisture and prevent odors. Colored paper, like construction paper, is really good for this since it is thick and has a slight scent of its own. Soak cereal in soapy water and also prepare it for composting.
Dry and Stale
This is one of the best forms to apply directly to the plant. Dry cereal grains can be ground into a powder and placed around plants. The sugars in the cereal promote microbial activity, and scraps of food or yard waste can be placed over top to work it into the soil faster. Stale cereal serves no purpose and will likely be thrown in the trash, so reducing the waste by composting it is easy and good for the environment.
Wet kitchen scraps and types of manure can be added to a large number of cereal grains to increase nutrient levels and add to compost material diversity. Both wet scraps and animal manure can use dry substances such as cereal to help them break down. Make sure to add carbon-rich materials like coffee filters and other dry foods.
Soggy and Old
In humid climates, old cereal may become spongy and soggy rather than dry and brittle. When this happens, you will only want to add it to compost with a lot of brown material and some vegetable scraps. Too much moisture on cereal grains can lead to mold growth which can harbor plant diseases.
Soggy cereal can lead to disease pathogens and dead plants if it is not properly dried out and composted. Lots of organic materials and even some acidic materials can help the cereal breakdown process run smoother. Pine needles and other green materials help to balance the carbon-to-nitrogen ratio and mask the grains from hungry pests.
Are Cereal Grains Good for Compost?
Most cereal grains are good for composting. They will enrich the soil and add organic nitrogen that plants can easily absorb. Cereal milk should always be discarded, but waste products like recycled paper and shredded paper can absorb any that remains on the cereal.
Soaking grains in soapy water can help prepare them for composting and allows them to break done faster. The cardboard boxes make usable compost, but the plastic cereal box liners can be recycled, not composted. Regularly adding cereal and boxes to your compost mix will help improve your soil, as long as you match it with a layer of nitrogen.
Breakfast Cereals Good for Compost
Some cereals are better for composting than others. There are hundreds of types of breakfast cereal, and some add value, whereas others just take up space. If you plan on using breakfast cereal as a source of compost, you will want to find grains that still have raw materials.
Shredded wheat, cheerios, and other types of whole grain cereals are quick nutrient deposits for starving soil. Adding these types of grains to your compost mix can help to improve the garden soil. A layer of pine needles will keep animals out and produce usable compost in several months. Yard waste products and high nitrogen content can balance the carbon-to-nitrogen ratio and improve the garden soil further, giving you better-finished soil.
Breakfast Cereals Not Good for Compost
Some cereals are high in sugars, dyes, and artificial ingredients. While adding a small amount of these breakfast cereals will not cause problems, too much might start to breed the wrong kind of microorganism. Annoying pests and insects also crave sugar and may be attracted to these types of cereals in your compost pile.
Cookies with cereal types and the very sugary, no whole wheat, non-enriched cereals add very little value to your compost. In reality, you would be better off dumping these cereals with high amounts of sugar in the trash and just composting the box. Sugar isn’t a good source of compost materials and will cause problems that can throw off pH balance and soil health.
How to Compost Breakfast Cereals
There are a few steps to compost cereal grains quickly, and make sure you are not adding any problems to your compost pile. All cereal added to a compost heap should be free of cereal milk and other dairy products. using recycled paper or shredded paper to remove excess cereal milk before composting is a great option.
Remove the cereal box liner and throw that in the trash or recycling bin, as it is not compostable. The box and all old, stale, or unwanted cereal can be tossed into the compost pile. The box can be cut up to speed up composting time. A layer of nitrogen can be added on top of the box and cereal to balance the materials. Organic nitrogen from the cereal will soon be available in the garden soil for plants, and you will have rich, fresh soil for planting.