Compost How to Make Hot Piles
(Step-by-Step Composting Instructions)

Compost How to Make Hot & Cold Piles: Essential Equipment

Click here to review the recommended equipment for easy composting.

Composting instructions follow one or both of two paths: the hot pile path and the cold pile path.

This page will teach you how to make compost using each method for dark, rich and healthy "garden gold"…


Hot vs. Cold Composting Instructions: What’s the Difference?

Compost How to Make Hot & Cold Piles: Composting Basics

Want to know more about why compost is important and why it's made the way it is?

See our Composting Basics page.

There are two types of composting piles: hot piles and cold piles. Hot piles get their name from being… well… hotter than cold piles. 140 to 160 degrees F (60 to 71 degrees C) to be exact compared to 70 to 90 degrees F (21 to 32 degrees C).

Before we dive further into their differences, let’s discuss their similarities. Both hot and cold compost piles require…

Kitchen Waste

DO add…

  • Bread
  • Coffee grounds
  • Coffee filters
  • Fruit scraps
  • Oatmeal
  • Tea bags
  • Vegetable scraps

DO NOT add…

  • Ashes (other than burned plants)
  • Dairy products
  • Diseased plants
  • Dog or cat manure
  • Lawn clippings from yards treated with chemicals
  • Manure from feedlots
  • Meat products
  • Roots of weeds (weeds above the roots are okay)
  • Weeds that have “gone to seed” (when plants produce seeds after flowering)
  • Nitrogen-rich or “green” ingredients such as kitchen scraps, grass clippings, bird feathers or even garden weeds.
  • Carbon-rich or “brown” ingredients such as straw, hay or leaves that have been chopped down to no more than 2 inches (5.1 cm) in length.
  • Soil or compost – your pile of compost is nothing without the organisms that will break it down. Since the organisms live in soil or compost, you’ll need to add some to your piles to get the decomposition started.
  • Air – There are good and bad organisms that can feed off of your pile… the good ones need oxygen and the bad ones don’t. The right amount of oxygen can be infused in several ways, including adding a layer of un-chopped straw to the bottom of your pile, turning the piles periodically or adding ventilation to larger piles. Any ingredients that can easily stick together and keep out air (such as leaves) should only be added to your piles in thin layers.
  • Water – The good composting organisms also need the right amount of water to do their job… moist but not soggy. An often-used analogy is this: your compost should be about as moist as a wrung-out sponge. If you squeeze your compost and a few drops of water come out, that’s good. If you squeeze it and water streams down your hand, you’ve added too much (this can be remedied by adding more dry browns).
  • Protection from the elements – To prevent over-watering by rain or the scattering of your piles by wind or animals, you’ll need to protect your piles. Composting bins, enclosures, tarps and plastic sheets are most commonly used.
  • Avoiding the wrong ingredients – the wrong ingredients could add disease or other harmful ingredients to your compost and therefore to your crops. Keep the following OUT of your composting piles:
    • Ashes (other than burned plants)
    • Dairy products
    • Diseased plants
    • Dog or cat manure
    • Lawn clippings from yards treated with chemicals
    • Manure from feedlots
    • Meat products
    • Roots of weeds (weeds above the roots are okay)
    • Weeds that have “gone to seed” (when plants produce seeds after flowering)

Now let’s get back to the differences…

In order to get up to the higher temperatures, hot compost piles must be built all at once rather than gradually over time. One of the upsides to the harder work involved when creating hot piles is the speed at which your compost will be ready. While cold pile composting usually takes at least a year to be ready for garden use, hot piles can be ready in as soon as two or three months.

Hot piles are also much better at killing garden weed seeds, something that a cold pile does not do. In addition, hot piles do a much better job at killing any disease-causing organisms than cold piles.

But don’t let these positives keep you from starting a cold pile which has one big benefit over its warmer brother: a waste-reducing outlet for your kitchen scraps and yard waste that still yields healthy, nutrient-rich compost.

Here’s a side-by-side comparison to make things simpler:

Compost How to Make... The Hot Pile The Cold Pile
Time until compost is ready Two to three months A year or more
Timeframe for constructing pile All at once Gradually over time
Compost ingredients More exact:
Between an 8 to 1 and 5 to one ratio of browns to greens
Less important (but still important)
Temperature inside pile 140 to 160 degrees F (60 to 71 degrees C) 70 to 90 degrees F (21 to 32 degrees C)
Weed seeds killed Yes No
Ideal timing for creation
  • Need compost more quickly
  • Composting materials readily available
  • Add materials more gradually (i.e. kitchen scraps, lawn clippings, etc.)

Long story short, finished compost from both hot and cold piles will be extremely beneficial for your garden… there is no safer, healthier or cheaper way to get your garden to thrive. Whichever pile you choose (ideally you’ll construct both), you’ll be happy with the outcome.

If you’re new to composting and aren’t in the mood to over-achieve, start making your own compost with a cold pile - also known as "easy composting" - and supplement your needs with pre-made compost. Graduate to hot pile composting when you feel ready.

Compost How to Make Hot Piles Stage 1: Preparation for Making a Compost Pile

Pre-Made Compost

If you’re just now getting your compost piles ready but are itching to start your garden, there’s no need to wait!

compost how to make

Good pre-made compost can be purchased to give your plants the nutrients they need while your homemade composting operation is getting underway.

The rest of this page focuses on how to make a hot compost pile. For cold piles, see our Easy Composting page.

  1. Choose the spots for your piles. A hot pile spot should be relatively close to your garden, should be “standalone” and should not lean against a fence or building.
  2. Build or buy a compost bin. Recommended bins are discussed in the last section.
  3. Prepare your composting pile spots by tilling or churning the soil. This will allow earthworms to get into the pile from below to help speed up the composting process. Hot compost spots should be at least 3 feet X 3 feet (0.9 m X 0.9 m) (by at least 3 feet tall after settling) to allow enough heat to build up within the pile. You may also want to add an un-ground, un-chopped layer of straw to the base of your pile to facilitate airflow.
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Compost How to Make Hot Piles Stage 2:
Starting a Compost Pile

Compost How to Make Hot Piles:
Compost Activator

compost how to makeCompost activator, also called compost starter or compost accelerator, will speed up the composting process and help to create a good garden soil pH balance within your compost.

It’s not absolutely necessary, but it’s a nice boost for beginners, those without easy access to healthy soil or compost or for those who need compost more quickly.

Click here to purchase compost activator.

  1. Create a layer of brown ingredients (straw, hay or leaves that have been chopped down to no more than 2 inches (5.1 cm) in length) that is a few inches (about 7.6 cm) deep.
  2. Add water to your brown layer... just enough so that it’s moist but not soggy. As mentioned above, the browns should have the moisture of a wrung-out sponge.
  3. Add a few inches (about 7.6 cm) of greens (kitchen scraps, grass clippings, bird feathers or weeds), making sure that the layer is just thick enough to avoid any clumping (remember, your pile needs air throughout for the organisms to thrive).
  4. Add about ½ inch (13mm) of healthy soil or compost to introduce the necessary organisms. If you need compost sooner than two to three months or don’t have healthy soil available, add compost activator at this step.
  5. Continue to repeat the above four steps until your pile is about 4 feet high (1.2m)… it should settle down to about 3 feet (just under 1 m) shortly. compost how to makeAfter your hot pile settles, it should be no less than 3 feet X 3 feet X 3 feet (91.5 cm X 91.5 cm X 91.5 cm) in order for the right amount of heat to build up inside. If it’s smaller, add more layers.
  6. If you’re not using a composting bin, cover your pile with heavy duty black plastic.
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Compost How to Make Hot Piles Stage 3: Manage Your Piles

compost how to make
  1. Using a compost thermometer, check the interior temperature of the pile on a daily basis. After it reaches its high temperature (between 140 and 160 degrees F /60 to 71 degrees C) in a few days, make sure it stays there.
  2. When you see the temperature drop, turn and fluff the compost-to-be, bringing the inside material to the outside.
  3. If the pile has dried out at all, add water back in while your turning it to return the mixture to wrung-out-sponge-like condition.
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Compost How to Make Hot Piles Stage 4: Use Your Compost

After all of your hard work and patience, how do you know when your compost is ready?compost how to make

Finished compost should have the following characteristics:

  • It should look like “healthy” soil: not too dry and not too wet without any identifiable ingredients. Finished compost looks like what it is: dark, nutrient-rich soil.
  • It should smell like “healthy” soil: it should not have a foul smell.

How much of it you need to add to your garden depends on your climate.

The same factors that caused your hot pile to decompose faster causes your finished compost to break down more quickly in warmer weather. Therefore, the warmer your weather is, the more compost you’ll need to add to your garden. Three inches in the hottest regions is probably not too much, while cooler regions may require as little as an inch.

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What Could Go Wrong? Potential Composting Problems

Good compost doesn’t always arrive without its share of difficulties along the way. Assuming you followed all of our advice above (pile is protected from the elements, right pile size, right ratio of browns to greens, right amount of soil, compost or activator, ingredients broken down into small pieces), there are still some things that can go wrong.

Here’s what to look out for and how to address each problem:

  • Temperature’s not right – it either needs more moisture (add water) or more air (turn and fluff, bringing inside material to the outside). If the temperature drops steadily and the pile has the right amount of air and water, your compost may be done! (See above for how to distinguish finished compost.)
  • Smells bad – your pile shouldn’t smell too bad while it’s decomposing. If it starts emitting a rank odor, you need to make some adjustments:
    • Too wet (again, wetter than a wrung-out sponge) – add dry browns
    • Needs air – turn pile inside-out and fluff
    • Smells like ammonia – add browns, turn pile inside-out and fluff
    • Be sure you’ve got a healthy proportion of browns to greens (ratio of between 8 to 1 and 5 to 1)
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Compost How to Make: Recommended Equipment

All Watering Cans
Are Not Created Equal

A watering can is just a watering can, right?

While it's true that all watering cans serve the purpose of delivering water where it's needed, there's a BIG difference between the cheap and the good...

compost how to make
  • Material - plastic is okay, but it won't last nearly as long as galvanized steel.
  • Design - a good watering can should be large enough to prevent multiple trips to the spigot but small enough to be a manageable weight. It should be comfortable to hold. Stopping and starting your pour should be effortless to allow you to deliver the desired amount of water. It should prevent spills if tipped over.
  • Nozzle - a gentle stream is essential for preventing plant damage or over-watering in any one area. Rose nozzles are perfect for this.

For a state of the art model that will last a lifetime, we use this green metal watering can.

For a good "cheaper" version, click here.

The hardest part of making compost is done for you by the organisms living in and breaking down your compost ingredients. These tools will help them do their job the most efficiently and productively:

  • Compost bins for hot piles should be at least 3 X 3 X 3 ft. (0.9 X 0.9 X 0.9 m). If they’re 4 ft. (1.2 m) or larger on the sides they should have ventilation slats. Cold pile compost bins should fit your lifestyle – the fewer greens you’ll have, the smaller the bin can be.

    Click here for a review of the best compost bin designs by category.
  • Kitchen Compost Pail - For easier storage and transport of kitchen waste
  • Soaker Hose or watering can for keeping your piles moist (see box to the right form more information about watering cans).
  • Chopping tool to break down the ingredients for easier composting, such as...Earthwise 20 Inch 12 Amp Electric Lawn Mower with Grass Bag
    • Lawn mower (easiest, especially if it has an attached bag for the clippings). If you don't have one and are looking for a solid option, check out the Earthwise Electric Lawn Mower (pictured below).

      In addition to being better for the environment, it's cordless, much lighter than its gas counterparts and comes with a easy-on/easy-off catchbag for collecting the choppings for composting.
    • Garden shears - The ergonomically designed Felco shears are extremely comfortable and easy to use. They also have a lifetime guarantee and are fully recyclable.
    Fiskars PowerGear 27 Inch Bypass Lopper
    • Loppers - for cutting thicker branches up to 2 in/51mm- This Fiskars PowerGear lopper (pictured right) is very lightweight, strong and sharp, and its gear mechanism provides leverage that makes pruning and cutting extremely simple.
    • Pruning saw for cutting branches thicker than 2 in/51 mm
    • Machete - The good old fashioned chopping tool is often enough to get the job done. While it requires more work on your part than a lawn mower or shredder, it's also the least expensive. This Kukri machete is one of the best out there: durable blade, proper balance, comfortable grip.
    • Shredder - If you're looking for a hard-core option that can handle branches up to 2.5 inches (6.35 cm) in diameter, go with the Patriot Products Wood Chipper/Shredder... you won't be disappointed.

      If you want something less expensive that can still handle leaves with ease, you're much better off going with the Earthwise Electric Lawn Mower mentioned above. Leaf mulchers/shredders do the job well, but for just about the same price the mower is much more versatile.

    Remember, the more finely your ingredients are chopped, the more quickly they will compost…but don’t forget to layer, turn and/or ventilate your pile to keep the bad organisms out!
  • Pitchfork or manure fork for turning and fluffing.
  • Compost thermometer so you know when your pile is ready to be turned, when any problems arise and when your compost is ready. Choose a thermometer with a longer probe that allows you to reach deeper into the pile.

Depending on the type of piles you have, you may also need the following:

  • Activators jump-start your compost by adding the right amount of microorganisms for perfect composting. They should be used if you lack healthy soil or compost to add to your piles.
  • Heavy duty black plastic for “open air” composting to reduce evaporation and keep rain out. If you use a plastic tarp, go with heat-absorbing black rather than heat-repelling white which could cool your pile below the desirable range.
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Finished compost photo for Compost How to Make pages is licensed under the Creative Commons Attribution 2.0 Generic license.

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