Quality compost is the silver bullet to a successful garden. It builds soil structure, improves drainage, adds micronutrients, fuels beneficial microorganisms, holds more moisture, and creates that luscious garden soil of your plant dreams. But not all compost is created equal.
Dry bagged stuff from big box stores often lacks the microbial activity and rich texture our gardens need. Conversely, luscious quality compost from an official producer or local organic farm can be extremely expensive.
Clearly, the best solution is to create your own. After all, you probably already have all the ingredients and tools you need. But the world of composting can be overwhelming! From worm composting to bokashi to specialized countertop devices, where do you begin as a beginner composter?
For the sake of simplicity, this article discusses good old-fashioned aerobic composting of garden and kitchen waste. Aerobic means oxygenated, as opposed to anaerobic piles that lack oxygen, leading to stinky rotten piles that never really become compost. An aerobic system usually looks like a steamy pile of leaves, veggie scraps, and grass clippings that you flip a few times to yield that dark brown crumbly goodness we all yearn to add to our garden beds.
Let’s dig into everything you need to know about starting a compost pile for your garden based on real science simplified into layman’s terms.
What is Composting, Really?
Compost is a product of decomposed organic matter that enriches soil for plant growth.
Compost is a rich, dark, earthy material made of decomposed organic matter (dead plant and animal waste). A controlled composting process involves billions of aerobic soil microorganisms that break down biodegradable matter into a rich amendment for nurturing the soil of gardens and farms, aiding in plant growth.
The key to successful composting is aeration. Many people mistakenly believe compost is a pile of rotten vegetables and yard debris. On the contrary, a properly constructed compost bin or pile requires regular aeration (flipping) and maintenance to ensure it has the proper ratios of materials to create a quality finished product.
Why Do Compost Piles Fail?
Successful composting takes some attention and nurturing to ensure a rich, earthy result.
Beginner composters often experience a lot of frustration with failed compost piles that never quite turn into the rich soil amendment they’re hoping for.
The main reasons why compost piles fail include:
- Improper carbon-to-nitrogen ratios
- Lack of aeration (forgetting to flip it)
- Inadequate moisture levels
- Excessive moisture
- Using it too soon before it is finished
Composting requires an attentive (albeit not super time-consuming) process of planning, building, and maintaining a pile until it is ready to use. It doesn’t take much time but requires a little effort.
Lazy composting doesn’t typically yield great results. Yes, a pile of biodegradable stuff will eventually break down, but it won’t always be pretty. It’ll probably smell disgusting. Real, finished compost smells earthy and delicious and doesn’t ooze any nasty slime. Creating this amazing amendment at home is really simple and cheap as long as you follow a few straightforward steps!
12 Steps to Create Microbially-Rich Compost In Your Home Garden
The whole point of compost is to boost your soil’s biological activity, structure, and water-holding capacity so your plants grow more happily, all while reducing your household and garden waste. In other words, composting makes gardening easier!
You don’t want to accidentally make your job harder by building a mess of a pile. Make a plan before piling up the leaves, grass clippings, and eggshells! Here is exactly how to create a fluffy, aerated, clean, and productive pile without the stink or hassle.
Know the Ingredients of a Healthy Compost Recipe
Approach composting as a recipe that requires measured carbon-to-nitrogen ratios, air, water, and specific ingredients.
Before you do anything, shift your mindset to think of compost as a recipe. This recipe requires measurements and “baking” time, much like a cake. The ingredients for a thriving compost pile include:
- Carbon-rich materials (“browns”) like dry plant debris, leaves, newspaper, and straw
- Nitrogen-rich materials (“greens”) like kitchen scraps, fresh crop debris, and grass clippings
- Air (oxygen incorporated through “turning” the pile)
- Water (consistent moisture)
- Thermometer (preferably a long compost thermometer to reach the center of the pile)
We will dig deeper into the ratios and process for assembling these ingredients, but you must be sure you can source everything you need in advance.
Choose a Composting System
A compost pile can be just a pile, but most home gardeners prefer the tidiness and accessibility of a specialized compost system that contains the decomposing matter. This is particularly important if you have a small urban or suburban space or any area frequented by wild animals and rodents.
Some of the best options include:
DIY Triple Bin System
Select a triple or quadruple-bin compost system to offer full containment through each stage of composting.
The triple or quadruple-bin system is the most popular among gardeners and farmers because it looks nice and makes it easier to flip your compost when necessary. The bins work in succession, meaning you start with raw materials in bin #1 and slowly flip the compost over as it breaks down, aerating and adding to it until it reaches the final bin, where it is stored until you’re ready to spread it in your garden.
You can construct a quality bin system out of wood from 7 pallets or scrap lumber and optional metal mesh. You can also buy a premade bin system like a wire or wooden composter kit. By making the front slats easy to slide out, you can adjust the bin height so it is easy to dump finished materials into a wheelbarrow or fill the bin up without lifting a shovel high over the edge.
The bins work as follows:
- Bin #1: Fill with raw materials according to the proper ratio (described below)
- Bin #2: Flip and aerate, monitoring the temperature regularly
- Bin #3: Final aging and cooling process
- Optional Bin #4: This is where you can store finished compost
Compost Tumbler
Consider a self-contained tumbler compost bin for easy turning and efficient composting.
Tumblers are completely self-contained bins, typically made of heavy-duty plastic. They are the easiest to turn because the handle or slots on the side allow you to simply crank and go! No shovel is necessary until the compost is done.
It’s easy to toss your scraps in from the bottom or the side (depending on the design) and help them heat up quickly with the power of the sun’s rays. The inside material doesn’t dry out as quickly, and built-in ventilation holes ensure continuous airflow. Best of all, tumblers are compact, aesthetically pleasing, and highly effective at keeping bugs and rodents out.
The downside to a tumbler is that because it doesn’t dry out as quickly after a heavy rain, the materials inside can get oversaturated, and you may need to leave the top open to allow some moisture evaporation.
Classic Pile
Opt for open-air composting, a cost-effective method involving layering and periodic turning.
Also known as “open-air” composting, this pile method is the cheapest and quickest way to get started. All you need is a shovel and some bare ground. This old-fashioned method is very simple but requires much more labor to manage unless you have a small tractor. As you construct the pile by hand, you will layer on the proper ratio of “browns” and “greens” until it reaches a sizable volume around 4 feet tall and wide.
The larger your pile is, the more likely the inner core will heat if it’s got the right ratio of carbon to nitrogen. A pile that’s too small (less than 3’x3′ in size) may never truly heat up inside.
When the pile begins to heat up, it’s time to “turn” or rotate it by flipping different material layers into a space next to the original. Remove the material from the outside of the pile first to form the core or center of the new pile. Then, pull material from the inner core to cover the new pile, creating a nice mixing of materials.
During the rotation, make sure the compost is as damp as a wrung-out sponge. If it seems a bit dry, hit it with the hose a couple of times while flipping it. This ensures it has the moisture it needs for good decay.
You must repeat the “flipping” process 2-4 times until the compost has thoroughly heated and broken down large chunks of materials.
Hardware Cloth Cylinder
Create a contained compost cylinder using hardware cloth, rebar, and a pallet for easy turning.
If you prefer to keep your compost more contained and reduce the amount of shoveling, try building a cylinder compost pile using hardware cloth, rebar, and a pallet. Leading soil biologist Dr. Elaine Ingham of the Soil Food Web uses this method.
Place the pallet on flat, bare ground and curve your hardware cloth (or a cattle panel) into a cylinder. Weave a rebar pole through the holes to hold the metal container in place.
Begin assembling the pile by tossing layers of scraps and carbon-rich material into the cylinder until it is full. When it starts heating up, remove the rebar to allow the cylinder to open, and the ingredients can fall out. Then, place another pallet to the side, reconstruct the cylinder, and use a shovel to flip the materials back inside, aiming to put the middle to the bottom, the bottom to the top, and the top to the middle. This ensures maximum aeration and oxygen in the decomposition process.
Choose a Suitable Location
Place the compost pile away from the home, on level ground, with proper sunlight.
Even the nicest compost piles attract bugs; you probably don’t want those near your home. Still, most bugs are beneficial, even the flies! Black soldier flies are actually some of the best insects to have near your compost pile because they lay eggs on the pile surface, and their larvae voraciously consume decomposing matter, creating richer compost more quickly. As a bonus, the black soldier fly larvae are especially desirable and nutritious for chicken feed.
The best compost location should be:
- Near your back door, but not so close that bugs become an issue
- On flat, level ground
- On a moisture-managing surface like wood chips, concrete, or hardened soil
- In a well-drained area where water can escape without creating a mucky mess
- In full sun to partial sun (in cool and mild climates)
- In partial shade (in hot climates)
- Covered (in wet climates to prevent a soggy pile)
The decision between sunny and shaded piles ultimately depends on your preferences and regional weather. A compost pile does need to be warm, but it can dry out too quickly if exposed to constant harsh UV rays, requiring more supplemental water.
On the flip side, a super shady area may keep the compost too moist, and things decompose much more slowly. Find a happy medium that works for your landscape.
Gather Your Inputs
Balance “browns” (carbon-rich) and “greens” (nitrogen-rich) for successful composting.
Before rushing to collect every seemingly biodegradable item in your home, it’s essential to understand the delicate dance of carbon-rich and nitrogen-rich materials in the decomposition process.
Carbon-rich “brown” material like straw, dried leaves, and non-glossy newspaper add carbon and structure to the pile. As you’ll see in the ratio recommendations below, you need far more “browns” by volume than you do “greens.” Too little carbon can result in a soggy, stinky, rotten mess. Too much carbon can cause a dry pile that takes forever to break down.
Nitrogen-rich “green” material like kitchen scraps, animal manure, fresh garden debris, grass clippings, and coffee grounds add nitrogen, enzymes, minerals, and moisture. These fresh materials are what heat up the compost and fuel microbial activity. However, too much nitrogen can cause a slimy, smelly mess. Too little nitrogen can yield a pile that never properly heats up and lacks nutrients.
Here is everything you should put in your compost pile, how to store it, and what to avoid:
Leaves
Utilize autumn leaves as a valuable carbon source for compost.
Autumn leaves are one of the most valuable and underrated garden inputs. Deciduous trees provide this rich source of carbon every year for free! All you need to do is rake them up and keep them in a pile for use throughout the year.
How to Store It
In my experience on over 15 different organic farms, the easiest way to maintain a compost pile is to keep a giant pile of dried leaves next to the pile at all times. You can continuously add to your leaf pile and keep an easily accessible pitchfork poked inside.
This allows you to grab a bunch of carbon-rich material to layer on top of “greens” every time you add inputs to the pile. I always keep a layer of leaves on the top of my compost to prevent odors and keep pests at bay.
What to Avoid
Avoid leaves from plants with allelopathic properties, such as black walnut, eucalyptus, and rhododendron. Allelopathic means these plants produce toxic compounds in their leaves to deter other plants from growing near them.
This is very beneficial when the leaves fall at the tree base because it reduces weeds and competition. However, if these weeds go into your compost pile, they may hinder crop growth when you apply that compost to your garden beds.
It is still possible to compost these leaves, but it takes significantly longer, and you’ll want to isolate them to their own pile. Let them fully break down on their own, allowing ample time for the pile to leach out its allelopathic components and neutralize any risks. As this means it’s a pile comprised of only “brown” waste, it can take a very long time for these to break down, but it’s worth the peace of mind to do this. Even after composting, it’s best to spread material made from allelopathic plant species out underneath the original tree that produced it.
Kitchen Scraps
Collect kitchen scraps in a countertop bin, but avoid composting meat, dairy, and oils.
Kitchen scraps include a little of everything – apple cores, banana peels, citrus rinds, and even meal remnants. Anything you set aside while chopping produce should go into your compost pile to be recycled in the garden.
How to Store It
The easiest way to collect kitchen scraps is with a countertop food scrap bin with a carbon filter. These are often made of metal or plastic and have an easy-access lid to toss things in while keeping gnats and flies out. These containers are sometimes wrongly called “compost bins” when they are actually designed just to collect food scraps. The food should not be composted inside the countertop container.
I like to collect scraps until the container is full or starting to smell, then I take it out to the garden and toss it in my pile. It’s important to regularly clean out your countertop bin to prevent pathogens, biofilms, or nasty bug colonies from forming. Avoid keeping kitchen scraps in the countertop bin for more than a few days; otherwise, they can become anaerobic and start fermenting on the counter. Gross!
What to Avoid
While it is certainly possible to compost meat, dairy, fish, and oil, it is not always viable on the home scale. Some home compost piles don’t get hot enough to kill pathogens and decompose the more complex molecules properly. In addition, many of these are particularly enticing to wildlife or even our own pets, meaning your dog might try to dig through the compost!
Fats, grease, and oils are tough because they create water-resistant barriers that slow the composting process. It’s usually best to put fats in the trash can so they don’t cause problems in your pile.
Processed carbohydrates like bread and pasta are typically only recommended in small amounts. Rice and smaller grains are fine. These are all technically biodegradable materials, but the composition of many modern gluten products makes them difficult to break down on a home scale, and they can attract more pests to the garden. If you want to compost an old loaf of bread or a bad batch of muffins, crumble them into small pieces and thoroughly mix them with other “green” scraps like fruit or vegetable odds and ends.
Garden Debris
Use garden debris like prunings, weeds, and old salad greens for compost, avoiding diseased material.
Finally, you have a reliable place to put all your tomato prunings! Fresh garden debris is an excellent source of “green” material if it comes from an actively growing plant and the tissues are still moist and pliable. If the stems or prunings are hard, rigid, and brown, they count as “brown” material.
Quality garden debris inputs for your compost include:
- Plants pulled out while clearing a bed
- Prunings and clippings from soft plant parts
- Weeds (without seed heads)
- Ugly or unsightly vegetable leaves
- Rotten fruit from trees
- Deadheaded flowers
- Used mulch
- Old salad greens
- Corn stalks (if dry, they count as browns)
How to Store It
When working in the garden, simply collect the plant debris in a bucket or wheelbarrow and take it straight to your pile. If you have any giant pieces of stems or larger pulled plants, use your pruners to chop them up into smaller chunks. Add a layer of “browns” over the top, and you’re good to go!
What to Avoid
Never compost garden debris that is infested with pests or diseases. Problems in your vegetable gardens will only worsen with time if you don’t export the material. As wasteful as it seems, throwing diseased plant material in the trash is important.
High-heat composting can break down pathogens, but many home compost piles don’t get hot enough to kill pathogenic bacteria or fungal spores. It is not worth the risk of spreading more disease in your garden.
Yard Waste
Transform lawn and garden waste into compost, but avoid herbicide-treated grass clippings.
Lawns and ornamental garden beds offer a wealth of organic matter awaiting transformation into a rich soil amendment. As long as you don’t use any pesticides or herbicides in your yard, these materials are excellent additions to the compost pile.
| “Greens” | “Browns” |
| Fresh grass clippings Fresh ornamental leaves Withered flowers Green, pliable vines | Small pruned twigs and branches Coniferous needles Dried, brown grass clippings Deciduous leaves Acorns (in small amounts at a time) |
How to Store It
Yard waste is best added to the pile as soon as it’s collected. Empty your lawn mower bag straight into the compost and keep lots of carbon-rich material on hand to buffer the high nitrogen content.
What to Avoid
If your lawn is sprayed with herbicides of any kind, do NOT use the grass clippings in your compost pile. Once, a huge field on my friend’s organic farm had to be removed from production due to herbicide-contaminated compost. They unknowingly spread the compost (brought in from an off-site supplier), and their crops grew extremely slow, sickly, and warped as if infected with a virus.
They quickly realized that herbicides from grass clippings and straw were used in the initial compost. Unfortunately, most modern herbicides are persistent, meaning they remain in the soil and debris for a long period without breaking down.
If you have had your yard sprayed in the past, it’s best to send grass clippings to municipal yard waste facilities for at least one full year before considering incorporating them into your compost. You can also have your grass clippings tested for herbicides at a local university or soil laboratory.
Coffee Grounds
Use coffee grounds in compost if you choose to, but don’t worry about their acidity.
Coffee grounds are somewhat controversial in the garden world because there are many myths about how to use them. To start, coffee grounds don’t actually acidify the soil. They are also not a major source of drainage benefits (in fact, too many espresso grounds could lead to compaction).
Some studies show that caffeine can inhibit plant growth, but other science demonstrates that coffee grounds are completely safe once composted and won’t change the pH. The decision is ultimately yours to make!
How to Store It
Add coffee waste to your countertop kitchen scrap bin and toss in the pile as needed. This will count as “green” input.
What to Avoid
Avoid applying raw coffee grounds straight to your garden beds. Compost them first! If you use pure, unbleached paper coffee filters, those are fine to go in your pile as well.
Eggshells
Crushed eggshells enrich compost with calcium but may not address major deficiencies.
Eggshells are a valuable calcium-rich addition to the compost pile. They are considered a “green” nitrogen-rich material and are best crushed before adding to the pile. While they come from a chicken, eggshells are comprised of approximately 98% calcium carbonate. However, all solid calcium sources require time to break down in the compost and become a soluble, plant-absorbable resource. If you have a major deficiency, eggshells aren’t a quick-fix solution for the issue.
How to Store It
Collect crushed eggshells in your countertop kitchen waste bin. Some people like to dry their eggshells and powder them first.
What to Avoid
If possible, avoid putting whole eggshells in the pile, as they can take a longer time to break down. The finer you can break up the shells, the faster they will decompose. However, it’s still going to take a long time for the eggshell to truly provide a significant boost of calcium for your plants.
Paper, Newspaper, and Cardboard
Use unbleached paper and cardboard as carbon-rich materials.
Non-glossy paper, newspaper, and cardboard are excellent carbon-rich “browns” to use when you don’t have leaves or straw readily available. These materials regulate and absorb excess moisture so your pile doesn’t become soggy. They also add carbon and structure to the pile so it remains aerated.
Bleached paper is divisive among gardeners. Some use it, others do not. The choice is up to you, but remember that bleached papers may contain remnants of the materials used to produce that pure white color.
How to Store It
Paper can be collected from your office and household throughout the year in a bin. Bring to the pile any time you add a large amount of “greens.” The key is to remove all tape and glossy ink pages. Rip or shred the paper or cardboard beforehand.
What to Avoid
Some inks are OK, but large glossy magazine-style prints can sometimes be plasticized to give them that shine and smooth, glossy texture. They could also contain toxins you don’t want to add to your garden soil. If you’re uncertain, check with the source if possible; there are polished paper types now that are fully compostable and biodegradable. Most gardeners opt to skip these just to be sure they’re not adding plastics to the bin.
Junk mail can also seem a satisfying solution to a neverending waste pileup – just compost the junk! However, with any envelopes, remove the little plastic window in the front of the envelope as well as any of the glossy materials that may be within. Try to opt for things that don’t have any raised, plasticized text on them. Embossed materials are fine, but avoid anything with an obvious coating.
A Note on Manure
Use aged herbivore manure for a potent nitrogen boost in compost.
Aged manure from herbivorous animals is one of the best nutrient-rich ingredients for a compost pile. If you raise animals or you know someone who does, consider collecting manure from cows, horses, and chickens to add a potent nitrogen boost to your pile.
How to Store It
It’s very important to use proper sanitation when handling manure. Store manure in piles with blends of livestock bedding (like straw) and allow it to age before adding it to your compost. Better yet, try only to bring aged manure back to your garden and leave the fresh stuff to decompose in its pile near the animal pens.
What to Avoid
Avoid adding large amounts of raw manure to your compost, as this could expose you or your plants to harmful pathogens. A lot of carbon-rich material is needed to balance the nitrogen in fresh manure. Aged is always best.
Sparingly Use Wood Ash
Use wood ashes sparingly, as they will alkalize the compost. Do not add ashes to compost intended for acid-loving plants.
If you have a wood stove or fireplace, ashes are a readily available source of potassium that can help raise (alkalize) the pH level of your compost and garden soil. It’s very important to use this sparingly and only apply the resulting compost to plants that enjoy alkaline soil, such as brassicas and other vegetables.
Do not add wood ash to the compost you plan to use for acid-loving plants like rhododendrons or blueberries. With ashes, it’s safest to take a “less is more” approach, as excessively alkaline conditions may also slow the composting process or prevent the decomposition of other components, like eggshells, from occurring.
Be sure your wood ash is pure wood ash and that it does not contain anything else. Certain types of self-lighting fire logs contain material that may linger in the ash and cause chemical contamination of your compost pile; similarly, barbecue ash may be contaminated with charcoal binders or lighting agents.
How to Store It
A fireproof bucket near your wood stove or fireplace is all you need to collect ashes as they accumulate.
What to Avoid
Do not add excessive amounts of ashes. A small 12oz-16oz mason jar per 6” of pile material in a large compost pile (3’x3′ or greater) is more than enough. Heavy use could cause too high of alkalinity and accumulation of salts. This can be damaging to your soil and your plants. It’s also best to avoid adding wood ash straight to the garden unless you do so in the winter when plants are dormant.
Avoid Diseased or Pesticide-Treated Plant Residue
Beware of herbicide contamination, and avoid diseased or chemically treated plants.
Once you know what to add to a quality compost pile, you will start to see free organic materials everywhere! The most important consideration when collecting plant residues is contamination.
Never compost diseased plant matter or anything that may have been treated with pesticides or herbicides. These plants should go in the trash or to a municipal composting facility because they pose too many potential problems for home gardeners.
Balance the Carbon-to-Nitrogen Ratio
Maintain a simple C:N ratio of about three to four times more “browns” than “greens.”
The carbon-to-nitrogen ratio is the most important (yet most misunderstood) part of composting. It is often abbreviated C/N or C:N to describe the parts carbon to parts nitrogen. A ratio (or fraction) can be scaled up or down, no matter the size of your inputs and pile.
Fortunately, this is not as complicated as it sounds. You don’t need an intense chemistry background to understand C:N ratios. All you need is eyeball measurements.
According to Cornell University, the ideal C:N ratio for a compost pile is 30:1 (by weight). This means 30 parts carbon to every 1 part nitrogen. But every material has its own ratio (for example, corn stalks are 60:1 C:N, and chicken manure is 26:1). In layman’s terms, a 30:1 ratio really ends up looking like four times more “browns” than “greens.”
Instead of digging into a bunch of math, use this rule of thumb:
Use about three to four times more “browns” than “greens.”
To simplify things, I like to just scoop my container in the pile of leaves, straw, or shredded newspaper to use as a measurement. For example:
- If you have one 5-gallon bucket of “green” garden debris, add four 5-gallon buckets of “brown” leaves.
- If you dump a full kitchen scrap container into the compost pile, use that same container to dump in three or four scoops of leaves on top of the kitchen scraps.
- If you put a whole wheelbarrow of cleared tomato debris into the pile, add three wheelbarrows worth of “browns” to balance out the high nitrogen.
- If you dump a lawn mower bag of grass clippings, add three times that volume worth of “browns.” In other words, imagine filling your lawn mower bag three times with leaves.
Measurements do not need to be precise and exact. The most important thing is to guestimate the volume of the material to the best of your ability. Balancing the ratios every time you add materials will make it much easier to manage over time.
Keep It Moist
Maintain even moisture in your compost, adding water if dry and protecting it from heavy rain.
Microbes need to drink, too! A compost pile should be evenly moist but never soggy. In the hot summer months, it helps to water down extra dry materials like paper or leaves. If your pile isn’t getting hot, you may need to moisten (but not saturate) the materials. If it smells bad, there is probably too much moisture, and you need to let it dry out.
Feel the pile periodically as you assemble it, and drizzle on water anytime it looks super dry. Protect your compost from heavy rains to prevent sogginess.
Track the Temperature
Use a long thermometer to monitor compost temperature.
A long thermometer is your best friend for composting. Stick this into the center of the pile to monitor the temperature. Beneficial decomposing bacteria thrive at temperatures between 110°F and 160°F. Hotter piles mean faster decomposition. Temperatures above 135°F are best for killing parasites, eggs, cysts, and flies.
Once a pile is full and cooking, put the thermometer in and wait a few days until it rises to around 140°F or higher. If you are worried about weed seeds or pathogens, let it get even higher. Once it reaches the peak hotness, it’s time to flip!
Flip at the Right Time
Turn actively decomposing compost every 3-4 days or when the temperature drops below 104°F.
According to Oklahoma State University, the best rule of thumb for turning compost is:
Once your pile reaches hot temperatures, actively decomposing materials should be flipped every 3-4 days or when the temperature drops below 104°F.
In tumblers, turn about two times per week.
Flipping the pile depends on your composting method but typically involves rotating the materials around. The center should end up on the outside, and the bottom should end up on the top. Everything should get thoroughly aerated and mixed together to promote a more even-textured end product.
If your pile is not getting hot, you may need to flip it open and add more “greens” to the core to help heat it up. Consider this a “restart” and wait up to a week to see if it heats the second time around.
Know When to Stop Flipping
Flip the compost until it stops heating up, indicating readiness for aging.
You’ll continue flipping your pile for a couple of weeks until it no longer heats up and everything looks decomposed. The timing is highly dependent on the inputs, management, and conditions.
A compost pile can take anywhere from 2 weeks (with regular flipping) to several months (with irregular flipping) to finish. Some people let compost sit for up to 6 months because they don’t want to actively manage the pile.
For a quick, hot composting process, the easiest rule of thumb is:
Keep flipping your pile until it stops heating up.
Once the pile stops steaming and you no longer see big chunks of food scraps, it is a good sign that your compost is ready to age.
Separate Finished Piles
Don’t add fresh material to an actively decomposing pile; use a three-bin system or multiple compost piles/tumblers.
Don’t add fresh material to an actively decomposing pile. This is absolutely critical for success! Once a compost pile is “in the oven,” so to speak, you don’t want to toss on a bunch more kitchen scraps.
Keep your actively composting and finished piles separate from where you collect the continuous stream of inputs.
The three-bin system is the easiest way to manage the consistent influx of ingredients. Your first bin can always be “in action,” while your third bin holds the aging compost.
If you’re considering a compost tumbler, look for a two-bin system. That enables you to have one side as an active addition location while the other one is “cooking”.
Allow to Cool Before Applying
Don’t use hot compost in your garden. Let it cool and age first.
Never ever apply hot compost to a garden bed! If the pile is hot, microorganisms are still actively breaking down the material. This means any seedlings you plant into hot compost may get killed by the heat and broken down as well!
Always let your compost cool and “age” for at least 3 to 4 weeks and up to 4 months after it goes through the heating and cooling cycles. The pile should no longer be steaming and should feel cool and rich to the touch. If the pile smells earthy and aged like a forest floor, this is a good sign! If it smells stinky or rotten, you may need to go back some steps, add more carbon, and flip more regularly to get it to heat up.
Sieve Your Compost
Use a sieve to determine the particulate size of your compost or to remove large, uncomposted material.
If you really want your compost to be as good as the “black gold” you’ve purchased in the past, sieving is the final step to success. A sieve is a simple wire mesh mechanism to remove large chunks from your compost. I prefer to use a few different sizes of sieves for different uses.
For example, a fine mesh sieve is only ideal for compost used in a seed-starting mix. A medium-mesh (1” holes) is great for potting mix. A larger sieve (2-3+”) is best for compost that you want to add to the top of your garden beds. It’s important not to over-sieve compost for your beds because the aggregates (larger clumps) are actually very beneficial to soil structure.
Final Thoughts
Composting is certainly confusing at first, but once you experience the process firsthand, you’ll realize that nature is remarkably intelligent. Remember that inputs and conditions are always changing, so adaptability and observation are a must. Even veteran farmers sometimes struggle with their compost piles. If your pile doesn’t heat up or it gets too soggy, don’t worry! You can always add more material and keep flipping to increase oxygenation.
The simplest way to sum up composting in your home garden is:
- Build a compost bin system, or buy a tumbler and place it in a partially sunny location.
- Gather “green” and “brown” materials from your kitchen and yard.
- Layer materials in the bin, adding about 3-4 times more “browns” than “greens.”
- Keep the pile moist but not soggy.
- Monitor the temperature with a compost thermometer, aiming for at least 135°F.
- After a few days of hot steaming, flip the pile with a shovel or pitchfork.
- Let it heat up again, then flip 2-3 more times or until the pile cools down.
- Let the compost cool and age for a few weeks.
- Optionally, use a sieve to get a finer texture.
