THE WASHINGTON POST – When done correctly, composting your food scraps and yard trimmings transforms them into a nutrient-rich fertiliser, reducing your carbon footprint and helping your garden all at once. Without the proper care, however, your good intentions could be rewarded with a smelly, unusable mess.
Among the most common signs that something has gone amiss with your compost: It’s soggy, it smells bad, or it’s just sitting there, not turning into anything at all. We spoke to experts about the mistakes that often lead to these (and other) undesirable outcomes – and most important, how to remedy them.
THE GREENS AND BROWNS ARE OUT OF BALANCE
Compost is a balance of oxygen, water, nitrogen and carbon. In composting parlance, the nitrogen part is known as “greens” and includes yard trimmings and food scraps.
The carbon part – aka “browns” – includes dry leaves, paper, cardboard and wood clippings. Urban farmer and lead soil researcher for Rosy Soil Justin “Jules” Guiliano recommends a 50/50 balance but said, “based on what you’re putting in, you might need a little more of one or the other”.
If your pile looks dried out or isn’t transforming into compost, you may need to add more greens. If it smells like garbage or seems overly wet, that’s a signal to incorporate more browns.
THE COMPOST PILE IS TOO WET
A pile can become too wet or soggy by adding too much water, receiving too much rainfall (if your compost is in an open container), or from an excess of kitchen scraps.
Compost with the right amount of moisture “should be about as wet as a wrung-out sponge,” said author of No-Waste Composting Michelle Balz. “So if you were wearing gloves and you reached in your compost and squeezed it, if like one drop of water comes out, then that’s good.” If a lot more comes out, try adding more browns.
THE COMPOST PILE IS TOO DRY
On the flip side, a compost pile can become too dry without enough water. If it’s crumbly in texture, light brown in colour or the waste is not decomposing, your compost is probably dehydrated, said Executive Director of the National Garden Bureau Diane Blazek.
Programme manager Ilse Rojas-Hamilton for Compost Cats, within the University of Arizona’s Office of Sustainability, explained that where you live plays a role, too.
“For example, in the desert in summer when we have 104-degree heat every day, we do need to water the compost more often.”
The remedy is simple: “If it’s too dry, stir it, water it and add more green products. Kitchen scraps are perfect,” said Blazek. She recommended touching the compost with your bare hands to check moisture.
TURNING YOUR COMPOST TOO OFTEN OR NOT ENOUGH
Stirring or mixing the compost pile helps the decomposition process by adding oxygen. “A lot of the microbes in a compost pile are aerobic, meaning they need at least some air, which allows them to multiply, to breathe and to break down your compost faster,” said Guiliano.
If you don’t turn your compost enough, you’ll notice it smells like ammonia.
The experts we consulted gave varying opinions about how often you should turn a compost pile, ranging from as frequently as two or three times a week, to as little as once every week or two.
Turning your compost too much is also possible. “The fungi and microbes that break everything down will keep getting mixed around before they have a chance to get to work,” said horticulturist Janet Sluis, who is also the curator for Sunset Plant Collection. “It can also really cool off your compost, which can stop it from decomposing.”
BEING IMPATIENT
A variety of factors influence how long it will take your waste to turn into nutrient-rich, ready-to-use compost. “It’s going to take time,” said Blazek. “It could take a year or two.” To set realistic expectations, first figure out your USDA zone, which is based on the average minimum winter temperature where you live. “How you compost in Toronto will be different than composting in Dallas,” said Blazek.
She shared her personal experience: “I put in my shredded leaves in the fall and then it freezes because I’m in zone 5, so it’s not going to decompose over winter. In the spring, I can’t go out there thinking I’ll have all this nice compost. I have to stir it after it’s been frozen all winter.”
In her case, Blazek said it usually takes about six months for her compost to become usable after the winter freeze. But if the compost was almost ready before winter, it could be ready within a month.
“Timing is dependent on so many factors that it’s hard to put an exact time frame on the process,” she said.
Other variables, such as how frequently you turn the compost and imbalances in the pile can also affect how long it takes compost to develop.
ADDING THE WRONG FOODS, OR TOO MUCH FOOD
Not all food waste is meant for the compost pile. “You don’t want to compost meat or cheese or anything that’s too oily,” said Balz.
These types of scraps can attract flies, rodents and wildlife, such as raccoons, or produce odours.
“If you have a salad that’s covered in dressing, it’s probably best to leave it out,” she said.
Even though it will decompose, it will smell like garbage, which you presumably don’t want.
Fruit and vegetable scraps, eggshells, breads, cereals, grains, spices, coffee grounds and tea leaves are fine for your compost pile.
But adding too much food waste can also lead to an excess of moisture and create compaction, which limits airflow and causes bad odours.
ADDING WEEDS OR DISEASED PLANTS TO YOUR COMPOST
Some plants shouldn’t go into a compost bin, even if they are considered “greens”. If you have plants that you know or suspect to be diseased, leave those out.
Otherwise you may spread diseases or pathogens around your garden when you use the compost as fertiliser.
Same goes for weeds: “You don’t want them in your compost because they will just proliferate in there and then you’ll have more weeds every time you use your compost,” said Sluis, who instead tosses them into her city green-waste bin. – Lauren David
