How to Compost: Hot and Cold Methods

Guide to making earthy compost for free – quickly and efficiently.

November 17, 2020
Supercharge Your Compost Heap

Composting doesn’t have to be complicated. See how to turn garden waste and kitchen scraps into nutrient-rich goodness—whether it’s “hot” composting or “cold” composting. Our guide will show you how to make beautiful, earthy compost for free – quickly and efficiently.

What is Composting?

Composting is simply decomposing organic matter—mainly from fallen leaves, grass clipping, plant debris, and yard waste. What would you might normally throw away decomposes into a soil amendment rich in nutrients that helps plants grow!

Hot, or Active Composting

The best way to produce rich garden humus is to create a hot, or active, compost pile. It is called “hot” because it can reach an internal temperature of 160°F (140°F is best) and “active” because it destroys, essentially by cooking, weed seeds and disease-causing organisms. The size of the pile, the ingredients, and their arrangements in layers are key to reaching that desired outcome.

Size: A hot compost pile should be a 3-foot cube, at minimum; a 4-foot cube is preferred. The pile will shrink as the ingredients decompose. Consider keeping the contents in place with chicken netting; wooden sides would be even better to keep the pile contained.

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Ingredients:

  • Browns:  High-carbon materials (shredded, dry plant matter such as leaves, twigs, woody stems, corn cobs, cardboard that is plain type and not glossy). If your ingredients are dry, moist before adding to the pile. 
  • Fresh Greens: High-nitrogen green plant matter (green plant and vegetable refuse, grass clippings, weeds, trimmings, kitchen scraps—but avoid meat, dairy, and fat)
  • good-quality soil

Ideally, you want approximately two parts “browns” to one parts “greens.” In reality, achieving the precise mix is hard but keep that “ideal” mix in the back of your mind.

Note that shredded leaves, chipped wood, and chopped food scraps generally decompose more quickly than whole or large pieces.

Directions

Cutting up or shredding materials helps speed up the process. 

  1. Pile the ingredients like a layer cake, with carbon materials on the bottom (twigs and woody stems here will help air to circulate into the pile).
  2. Next, cover the layer with soil.
  3. Add nitrogen-based materials, followed by soil. Repeat until the pile reaches 2 to 3 feet high.
  4. Soak the pile at its start and water periodically; its consistency should be that of a damp (not wet) sponge.

Add air to the interior of the pile by punching holes in its sides or by pushing 1- to 2-foot lengths of hollow pipe into it.

Check the temperature of the pile with a compost thermometer or an old kitchen thermometer. A temperature of 110°F to 140°F is desirable. If you have no heat or insufficient heat, add nitrogen in the form of soft green ingredients or organic fertilizer.

    Once a week, or as soon as the center starts to cool down, turn the pile. Move materials from the center of the pile to the outside. (For usable compost in 1 to 3 months, turn it every other week; for finished compost within a month, turn it every couple of days.)

    Video: See exactly how to make beautiful, earthy compost for free – from start to finish!

    Cold, or Passive Composting

    Cold, or passive, composting requires less effort. You essentially let a pile build and decompose, using the same type of ingredients. 

    It requires less effort from the gardener, yet the decomposition takes substantially longer—a year or more.

    To cold compost, pile organic materials (leaves, grass clippings, soil, manures—but avoid dog, cat, and human waste) as you find or accumulate them. Bury kitchen scraps in the center of the pile to deter insects and animals. Avoid adding meat, dairy, and fat. Also avoid weeds; cold compost piles do not reach high temperatures and do not kill weed seeds. (In fact, weeds may germinate in a cold pile.)

    Compostable Goods

    In addition to the ingredients mentioned above, any of these items may be added to a compost pile:

    • Coffee grounds and loose tea or compostable tea bags (note that most tea bags are not fully compostable so tear them before adding to compost)
    • Dry goods (crackers, flour, spices)
    • Eggshells
    • Hair
    • Nutshells
    • Pasta (cooked or uncooked)
    • Seaweed
    • Shredded paper/newspaper

    Learn more about composting “in situ” or in place.

    Composting Problems and Solutions

    1. Avoid soggy piles by alternating wetter ingredients (such as fresh grass clippings) with drier and more fiberous ingredients (such as dry leaves, cardboard, woodier crop residue). The resulting mix should be damp but not sodden. You can also sprinkle wood ash onto your heap but, importantly, it must be wood ash and not coal ash.
    2. Avoid cooked food waste and animal products like meat and dairy which attract rats. If rodents are a problem, ease off adding potato peelings which are a favorite snack.
    3. Avoiding dumping your fall leaves into the heap all at once, which slows things down. Add them in modest qualities along with fresh green ingredients. Or, compost them separately over one or two years as leaf mold. See how to make leaf mold.
    4. Weeds are fine but make sure they haven’t set seeds. Avoid invasive perennial weeds such as bindweed. 
    5. If a foul odor emanates from the pile, flip the compost to introduce more air.  Mixing the compost heap not only gives it plenty of air, but give it a finer end product that is easier to spread.

    Tips to Supercharge Your Compost!

    One way to supercharge your compost is to include ingredients with a very high nitrogen content. Animal manure or bedding from chickens or pets like rabbits is powerful at firing up decompoistion. Nettles are another great booster while urine is also a famous compost activator. Add it directly. 

    Take the plunge and get composting! You’ll feel great doing it. Or, if you’re already composting, share your tips for supercharging your compost! 

    Enjoy this video? Find more videos, tips, and techniques to grow your own food! Sign up for our online Garden Planner here: http://gardenplanner.almanac.com 

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    Reader Comments

    Leave a Comment

    Adding to the compost pile

    I love all the composting instructions that seem to assume we all have a large quantity of "stuff" to compost all at once. "Pile it up together, in these proportions, keep it somewhat moist, turn regularly, and voila! perfect compost!" Except for autumn leaves, I expect most people are like me, I have food prep "stuff" to add almost every day. So I keep a large plastic coffee canister by the kitchen sink. Peels, cores, oops-that-lettuce-is-past-its-prime, tea bags, coffee grounds (WITH the filter), dead leaves from houseplants - you get the idea. When it's full (1-3 days) I carry it out to the compost "bin" which is a 30-gal plastic can that split slightly on the bottom. I usually layer in some grass clippings that have been drying in the sun for a couple days. I rinse the coffee canister and add that to the barrel. Now and then I turn the garbage can on its side and roll it around a few times, which is a technique I found in another Almanac article, and works surprisingly well to "stir" the pile.

    I'm about to shut down for the winter - the compost cooks great in the summer, but is pretty inactive in the winter here in TN (I would expect even worse results in a colder climate). Last year I turned the barrel top down into the garden and let it sit like that for the winter. In the spring I had a small pile to till into the garden. Lesson learned last year - grapefruit halves don't degrade! Previous years lead me to exclude banana peels, and really fresh grass clippings, both of which get slimy quickly and take forever to proceed. I also don't bother with eggshells as they stay intact - I'm sure they're a useful addition to the soil, but I don't want the bother of grinding them up.

    When I restart in the spring, I'll start with at least 6" of small twigs and tree trimmings. They help aerate the pile to start with, and by the end of the process they disappear too.

    I beg to differ about tea

    I drink a lot of tea, especially at work (until I retired!). I collected used tea bags at work in a gallon jug, brought them home and forked them into the compost pile every couple of months. I rarely saw ANY residue from the previous additions. A lot of what I drink is tagless, and those brands definitely do NOT use plastic mesh. But even the brands that have strings and labels disappeared completely. Well, I suppose I could have filtered the finished compost looking for the tiny staples that attach the string to the bag and the label but I've never thought that was worth the effort.
    If I found plasticized tea bags in my compost, I expect I would have thrown them away in the future, the amount of tea leaves involved are not worth the effort (to me!) to dismantle the tea bag for my compost. Also, I might just change brands :-)

    Compost for Soil

    Hi, I have a few questions. Is it natural to have mold or fungi in the compost since they decompose? Also do I have to sterilize the compose before using in my garden, like I have heard you heat up soil to kill bacteria that might cause disease to plants? Thank you for the help I have learned a lot!

    Hi! I've had a lot of

    Hi! I've had a lot of experience with hot composting, but I'm farely new to cold composting.... A couple of questions:
    1. How often should a pile be turned?
    2. Does it have to be kept a certain temperature? Is it okay for it to be in the sun?
    3. Is there an issue with putting too much food waste? My idea is that food would be put in every day. Could it be buried or should greens and browns go on top every time?
    4. If your placing new in every day how is it ever ready?

    going cold compost

    The Editors's picture

    There really is little that you need to do when cold composting. This is essentially a “wait for it to rot” method. Turn the pile or mix it when you add new ingredients. There is no particular temperature to achieve or exceed; let nature take its course. If you make your pile one of primarily food waste, it could be a slimy rotting mess. (Ever seen food rot in a bag or container without benefit of browns or greens?) It would be better to add natural ingredients as you would a hot compost (see the lists above in both the hot/cold sections). Certainly some of it will be “ready” before other of it (this might be on the bottom or on the side) simply because the older portions will have had more time to rot. If you have an abundance of compostibles, it might be worth having more than one pile. Then you will have a better track of what’s ready when.

    Moon

    Hello my name is caitlin Bartula and my question is..... Is the moon hot or cold???

    Moon's Temperature

    The Editors's picture

    In short, both. The average nighttime temperature is –298°F and the average daytime temperature is 224°F. Because the Moon has no real atmosphere to block the Sun’s rays during the day or to trap heat at night, temperatures vary greatly between day and night.

    Can a cold pile be heated up

    I have about 4x4 compost pile started last May, using pallets. I think I may have had too much nitrogen and my pile never heated up. I turned it, kept it moist and added quite a bit of carbon, but still never heated up. Every time I turned it, the middle was cold. Is there any way I can get this pile cooking now this spring? I'm concerned that some seed from last year's material will not be killed off and I don't want to add this to my garden if I'm unsure of what I'm going to get. It smells "earthy" and is decomposing nicely but I don't want the headache of seeds or disease in my garden.

    Cold pile

    The Editors's picture

    It sounds like you’re doing all the right things … Below a certain size, piles will not heat up. You’rs is slightly larger than the min (3x3 feet). Dead leaves compost slowly because they are high in carbon. Same with grass clippings. You say it’s moist; maybe it’s too moist: Does water drip/run out if you squeeze a handful? Maybe you have a paucity of microorganisms. These can come from the ground beneath it. If your pile is on pallets, it is not making contact with the ground. (Same for building a pile on plastic or cardboard, etc.) You can add ordinary dirt, but it will not produce a swift result. For that, you could purchase an inoculant of microorganisms. Adding fresh (hot) compost will contribute microorganisms, too.

    Hope this helps—

    compost

    A 4-foot cube is a minimum. I have a simple wire fence circle about 8' diameter, which I fill up to nearly chest deep with all my clippings and leaves as well as those of several neighbors. I water the pile as I add to it (like a damp sponge) during the fall. It is too big to turn, so I bought a cheap pitchfork, knocked the metal part loose from the handle, and then mounted it at a 90 degree angle on one end of a 6' stripped sapling. I just plunge the fork, which is now angled like a hoe or rake, deep into the pile, and give it a small yank, thus getting air into the pile. It shrinks easily to mid-calf height during the whole year and the resulting compost is a breeze to scoop into a wheelbarrow to spread in the garden!

    I heard that grass clippings

    I heard that grass clippings that have been treated with weed killer can be added to cold composting piles as long as pile "cooks" for at least 18 months. True?

    Hi, Mike: This is too general

    The Editors's picture

    Hi, Mike: This is too general a statement to be deemed true or false, as the answer can depend on the chemicals involved, decomposition process/rate, and a number of other factors. We wouldn't do it under any circumstances, though. Thanks for asking!

    I am thinking about using

    I am thinking about using metal barrels (55 gallon drums) for composting in containers (I'm scared of attracting rats). Has anyone had any experience with this? They are black and have lids so I think they will get hot enough. What I am not sure about are: do I have to turn it? and do I still need to layer brown and green materials?

    Also, anyone mix food/foliage compost with chicken manure?

    Thanks!

    Hi, Shontael: 55-gallon drums

    The Editors's picture

    Hi, Shontael: 55-gallon drums are usable, but this is a lot more complicated than it may appear. You would need to be absolutely sure that they were decontaminated. Usually they are used on their sides and rotated to turn. They also need at least a little ventilation. Just throwing compostable material into a vertical drum and then sealing is usually not done for a number of reasons, not least of which is that it is a lot more difficult to turn than you might imagine. Do some research to ensure a successful project. And while you can certainly use chicken manure (or a diluted solution of aged chicken manure) in conjunction with compost in the garden, you would not want to add it directly to your compost bin. Thanks for asking!

    Composting

    I use to have 6 old plastic garbage cans with holes in the bottom from dragging them to the curb for my mulch bins. The hole(s) must be in contact with the dirt, that's how the worms come in. They were lined up at the side and back of my garage. The garage had a hip roof. I made plywood covers with holes in them to allow water to come in and keep down the evaporation with the ones in the sun. Grass was cut by the gardener and he was instructed to leave the pile on the ground near the beds. Green grass was spread over the bed and by the following week was brown. Covered that with some fresh clippings and tilled that into the beds. Greens and browns. Left over clippings went into each can just as a light top cover. Too much and the grass will sour and smell like there is no tomorrow. When the cans started to diminish in size I combined them. By late fall I ran the compost through a wire diamond mesh lath in a 2x4 frame over a wheel barrow. Left over material when back into the pails. Worms galore and I wound up with about 5 - 5 gallon pails of incredible mulch. On the lawn around the trees and dug the rest into the garden beds. The top soil went from 4" thick to 12" over 20 years. Loved ever minute of it. And the produce was top notch. All organic. The worms were a plus for fishing. Always left some behind.

    Tea bags should NOT be added

    Tea bags should NOT be added directly to a compost heap. Open them and empty the contents into the compost. The 'bag' is made from plastic net impregnated with paper. The paper rots, but the plastic does not. I stopped using the bags over 5 years ago but am still digging them up each year when turning over the soil, still with their contents trapped inside.
    Egg shells should be dried, then ground as fine as possible before adding.

    Thank you for this. We've

    The Editors's picture

    Thank you for this. We've updated the article to add this point about composting tea bags.

    Composting can be done in

    Composting can be done in many ways, I use a hot method but my pile is quit large so I take a piece of black PVC six feet tall then I drill 3/4'' holes on opposite sides 6" from the bottom then again 1" above that but on opposite sides. Do this pattern every 6" up the pipe to the top, then I take the pole and put it in the center of the compost pile vertically with a cap loosely on top to regulate the heat. I then layer my pile around it, mine is about 7' wide by 6' or more high. I then get the pile moist but not wet & I turn the pile about every five days. Once the heap is hot I will remove the cap to airate it. This works well for me, my garden is approximately 50x50 this gives me all I need. I hope this is helpful -MTE

    I am new to this as well, so

    I am new to this as well, so a few questions about hot composting?

    Once I have built up my 3 foot compost lasagna can I keep adding to it or other than turning it, do I just leave it alone?

    Just wondering how to hot compost during the winter. Can I build my 3 foot compost lasagna and just continually add to it over the winter and keep turning it?

    I am assuming a couple 4x4x4 boxes are necessary and rotated through over the growing season?

    Lastly, would it be advisable to have a plexiglass/glass/plastic lid over top of the compost bin to help cook the compost over the winter?

    Lasagna beds are designed not

    The Editors's picture

    Lasagna beds are designed not to be turned -- they’re a form of no-dig gardening. Composting materials are added in layers -- like in a lasagna -- and not mixed together.  They rot naturally and worms and other soil micro-organisms do the mixing. Add as much as you need to create the bed but remember it will sink as the materials rot.
    When composting in a bin (rather than piling composting ingredients where you will be planting) you can keep adding material until the bin is full and then leave it to rot - it’s a good idea to have an extra bin or two that you can turn to when the first is full. Composting is a slow process and may take anything from six months to two years depending on many variables such as your climate, the weather, and the materials you’re adding to the bin. In my experience it usually takes around a year. Mixing in grass clippings (not too much though, and not in thick layers) does speed things up a little.

    During the winter composting

    The Editors's picture

    During the winter composting slows down dramatically -- depending on your climate there may be no noticeable changes in your compost over the winter. Turning it will introduce air into it and cool it further. 

    Boxes aren’t essential for

    The Editors's picture

    Boxes aren’t essential for lasagna gardening or for composting; it depends on how tidy you want your garden to look! Bins for composting (the larger, the better) can help the compost to heat up better than an open pile, and are less of a draw for rodents. If creating a lasagne bed inside a raised bed, plant into it just as you would into the open ground -- you will probably need to add some finished compost or good soil for plants to get started though.

    Hi there -- Here are some

    The Editors's picture

    Hi there -- Here are some answers to your questions. Starting with the last question:
    A cover will certainly help keep the soil slightly warmer, which is beneficial when you come to plant into it in spring, and will stop it from getting too wet, but you may need to check it occasionally and water it if it’s very dry.

    Thank you! I am new at this

    Thank you! I am new at this and was wondering if there are any suggestions on containers or building materails used for hot composting.

    You do not need a bin or

    The Editors's picture

    You do not need a bin or container to make compost. Piles work well. However, if you'd like a bin, to keep it tidy, it needs to be big enough to hold heat. A pile that begins with about one cubic yard of material is big enough for year-round composting, even where winters are cold. That means a bin about three feet wide, three feet high and three feet deep will be big enough to retain heat. If you Google, "Hot Compost Bin," you'll see some options.

    You can get compost and

    You can get compost and animal feed at the same time using bsfl (black soldier fly larva). They turn your compost for you, devour all types of organic material including meats and dairy, and are used for feed(chickens go nuts for them). Quickest time I've clocked is table scraps to complete compost in 5 days

    Do you use them in the "hot

    Do you use them in the "hot compost"? I'm a newby to all compost/gardening & want to be efficient :)

    Thanks for the interesting

    Thanks for the interesting article! I started 'growing my own dirt' last year, and love this earth friendly activity. Good hints here!

    I nurture my compost bins

    I nurture my compost bins year 'round. (Amherst, VA) Yesterday, I tilled in some beautiful new soil as I put my veggie garden to bed for the winter. Not only does it help my soil, I also get some interesting volunteers in my garden!

    Thank you for teaching me a

    Thank you for teaching me a little bit more about my own compost pile!
    Your Friend,
    Stormy

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