Hot Composting: Step-by-Step Guide

Hot composting can seem intimidating at first, but remember, this is a natural process. If you mess up, you can try again. Keep in mind that there are four elements you want to keep in balance: nitrogen (green stuff), carbon (brown stuff), oxygen (air), and moisture (water).

1. Choose a Compost Location

   First, choose a location in your backyard or garden that's convenient to the house, since you will be checking your compost often. Be sure you choose a shady, well-drained area. Locate it away from any structures since insects will be a natural part of the composting process.

   A hot compost pile needs structure to it. So, make or buy a compost bin. To make a quick and easy hot composting container, attach a piece of woven wire fencing or chicken wire to itself at the circumference you'd like for your compost.

   Whatever you use, it shouldn't be bigger than about 1 cubic yard of volume. That's about 3 feet wide by 3 feet long by about 3 feet tall—it doesn't have to be those exact dimensions but should hold about the same volume. This is to both create a system within which heat can build up and moisture is contained, but that you can also aerate easily.

2. Set Up Your Compost Site

   So, you've found a shady, well-drained site. Now, you can put the foundation down for your hot compost. Clear the ground so you have bare earth and place your compost bin or wire containment.

   Begin at the bottom of the container or enclosure and layer leaves, small branches, dry lawn clippings, newspaper, or torn-up cardboard—to a depth of six inches. This is your brown material and will serve as the bread in the compost sandwich.

   Make sure to vary the types of material, especially at the bottom of your pile—you don't want anything that mats together, like grass clippings, as your only base material. Lightly water the base.

3. Add Your Green Material

   For hot compost, you're better off adding larger amounts of green material all at once than smaller amounts more frequently. The ratio is two parts carbon (brown material) to one part nitrogen (green stuff), so you'll want to keep track of how much material you are adding.

   Add your compost, starting with a thicker layer in the middle and less on the sides, with a maximum of about 5-6 inches. That will be on top of the 6 inches of brown material you have already put down.

4. Layer and Measure

   Keep going with the layering—if you have saved up enough material, you can do two layers of green material to start, just remember to always end with the brown material on top and keep to the 2/3-to-1/3 ratio.

   As long as you stick to the types of scraps that can be composted when it comes to your green materials, don't compost things that shouldn't be (see list above), and keep your air and moisture conditions right, your compost won't smell and you won't have to worry about pests or rodents.

5. Maintain Your Compost

   In order to get your compost to the hot stage, which will lead to a faster and more efficient breakdown of materials, you need to keep it both aerated and moist. After you add your green material and layer the brown on top, lightly water your pile—distribute it evenly, and only to the level that it feels like a well-wrung sponge—it shouldn't be soaking wet or dripping.

   As you are saving up your kitchen scraps for the next compost layer, which should take a week or so, let the compost sit untouched; it will be naturally accumulating bacteria and microorganisms.

6. Take Your Compost's Temperature

   
   After two or three days of starting your hot compost, check its temperature using a compost thermometer. You are aiming for temperatures of between 141 F to 155 F. This is the temperature at which the seeds of weeds and disease pathogens are killed. You don't want it to go too much higher though—160 F and above will kill the bacteria and microorganisms you want to break down the materials in your compost. (If it starts to get too hot, just introduce some air by turning the layers over and aerating it.)

   Check your compost daily—it should maintain this temperature for a few days to a week.

   If the pile isn't hot enough, you need to add more nitrogen (that's the green stuff). If the pile smells, add more carbon (brown stuff).

7. Aerate Your Compost

   When you have enough kitchen scraps saved up, or in about a week, take them out to your compost bin—before you add them, aerate what's been "cooking" thus far. This means turning over those layers you created when you set it up. Then add your scraps, and add another layer of brown stuff on top at the 2/3 to 1/3 ratio.

   Finish by watering the whole pile—if the lower layers you have just aerated are pretty damp, then just add water enough to dampen the new layers of compost you have added. If you notice that the layers you have turned over are a bit dry, add enough water to ensure the whole pile is moist—remember those microorganisms work best and fastest when they are warm and damp.

8. Harvest Your Compost

   After 1-3 months (how long depends on how well you've maintained constant conditions in your compost as well as your local weather conditions) you should be ready to harvest your first round of compost. The pile should have noticeably decreased in size even though you were adding layers to it.

   Overall, you will lose a lot of volume—as the materials turn into compost, they will get 70-80% smaller. If you added a gallon of green material each week (so 3-4 gallons of brown), after a month you'll just have a gallon or so of compost. So, you may want to wait until month two when you'd have twice that much to harvest it, but that depends on what you're using the compost for.

9. Use Your Compost

   Your compost will be at the bottom of your pile—it will be a dark brown, crumbly material that smells pleasant and damp. There shouldn't be any recognizable pieces of what you composted left behind.

   You can add a couple of cups of compost for repotting houseplants (about 1/8-1/4 of the volume can be compost mixed with soil), or mix it 50/50 with potting soil when starting seeds.

   Add compost directly to the soil of a garden bed or container (for veggies of flowers) in the spring or after harvest in the fall. You can add it to the soil when planting trees and shrubs

   You can even use compost on your lawn in the spring or fall. You can simply sprinkle it over your lawn; aim for an amount between 1/8 and 1/4 of an inch thick.

Frequently Asked Questions

If I make my compost hotter, will it degrade material faster?

No, if your compost gets too hot (above 160 degrees Fahrenheit) it will kill the bacteria and microorganisms that do the important work of breaking down your compost. A too-hot compost will actually take longer to degrade.

How can I make my hot compost degrade material faster?

Three things can help accelerate your compost. The first is chopping your compost (both brown and green stuff) up into smaller pieces—with your kitchen scraps you can do this with a knife, and with the brown stuff you could run a lawnmower over leaves or small branches to chop them up.

The second accelerator is adding animal manure to your compost. You only want to do this once you get the hang of composting, because it's important that your compost get hot enough to kill pathogens. But if you are at this stage, you can add fresh chicken, cow, horse, or goat manure as a layer in addition to your browns and greens.

You can also add a compost booster to your pile. Add 1/4 cup molasses and a packet of yeast to a 5-gallon bucket along with a couple of shovel-fulls of soil. Add warm water to within a few inches of the top of the bucket, stir, and leave in the sunshine for a day or two. Then, pour this mixture into your compost pile.

Do I need to cover my hot compost pile?

If it's very rainy where you live, or you have a rainy season, you should cover your compost during that time period with a tarp or a cover if your bin came with one. If your compost gets too saturated with rain, it will become too soggy to degrade efficiently.