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Roger Doiron
Which is better: hot or cold composting?


Your neighbors are using two different composting systems: cold composting and hot composting. Both yield compost, but hot composting produces it faster than the cold method. To cold compost, simply toss ingredients in a pile or other enclosure, and then wait a year or two for them to break down. Turning the pile, which means moving the materials from one spot to another to mix them up, is optional, although tackling this task once or twice a year will speed up the decomposition process. Hot composting takes more time and energy to prepare but produces finished compost in about 3 months. It also lets you produce more compost per year in the same amount of space. Hot composting gets its name because all the microorganisms busily breaking down materials generate heat within the pile. Reprinted from The Veggie Gardener's Answer Book Copyright 2008 by Barbara W. Ellis, with permission from Storey Publishing. Photo credit: Seabamirum

Question details

I've got two neighbors. One just piles up his clippings, and the other one is always digging through them and moving them around. Which is the better way to make compost?

I know that you probably get the same result in the long run whichever method you choose, but hot composting gives you something else. A real sense of achievement when you get the pile to heat up.
You are SO RIGHT! It makes you feel good about the whole topic.
I have huge cold compost piles in wire rings. I like to see how they compress and degrade. At Thanksgiving they will be 4ft high with leaves, by Christmas they will be 2ft tall, and by next summer they will be ready to go! Slow motion rot!
Glenn, I thought of you when I saw this question! :-) I hope to hear more from you here. I also think of you whenever I see Parsnip seed. :-) I will be back with a considered response soon. Spent the blue sky morning biking around town to get wholesome fresh green grass clippings to designer-mulch my upcoming milpas garden plot. There's something satisfying about biking along looking absolutely Asian with three giant bags of grass clippings hanging off the handlebars & its easy because they're so light. :-)
Hi Jessica, It,s good to hear from you. I don,t get on here as often as i used to. I always seem to struggle to log on nowadays. I still think that compost is the cornerstone of any kitchen garden in producing a healthy fertile soil. Healthy soil = healthy plants = minimal problems. I still believe the hot plus cold method is the optimum method of making the best compost, using the three bin system. One bin for collecting the ingedients. One bin for making the hot heap. One bin for finishing the compost in a cold heap so the worms can come in and do their thing. Regards Glenn
Although the method must be selected depending upon your objectives and needs but Hot composting in general is much better. It offers many advantages like works for whole year, free from odors, rich compost basically etc.
Alan, those good attributes & more are true of advanced methods of cold-composting! I plan to write a blog post in the foreseeable future about my ten-years' experience with *so-called* cold composting - plus recent research findings - since the comment/software truncates comments randomly. Today they cut the same organic grass again as above & Angel delivered it to the gardens - with a promise of more from him & his brother!
Agreed. Hot has its uses, especially when you have a lot of raw materials to work with, but cold has many advantages, for the environment and potentially for the quality of the finished compost. Of course, I'll take either hot or cold any day.
Roger, I am new to this forum, but love the information and collaboration. I have been composting commercially for over 20 years and consult with large scale farms and backyard composters. My belief is that getting a pile hot does a few things. 1. It kills pathogens that can be put back into your soil and eventually end up in your food. 2. It will speed up the process and also weed out harmful microorganisms. 3. When making a hot compost pile and turning it often it provides consistency to the end compost product so when you plant in it or put it around plants it will preform the same from one plant to the next. Love the forum and the process of composting!
Welcome seangardener ! Your point 1. is timely for our community food bank garde, but I am thinking of plant pathogens rather than human pathogens. Last year they were given a big box of compost that is now known to have carried tomato leaf curl into the garden - where it also affected rhubarb, beans & peas to some extent. I have a private plot there in a program for people who do not currently have their own land. My garden will still be beautiful & productive with diseased Scarlet Runner Beans, because I have planted many good crops that are not susceptible to tomato leaf curl. For the moment, I am experimenting with adding microbial soil innoculant & surround-planting with innoculated Dutch clover to see if we can make any difference via the microbial life in the soil. And I have a query in to Paul Stametz @ Fungi Perfecti on that topic which will be answered in due time. Here is a question for your history of expertise in composting >>> the garden director has said they may excavate the beds that got this bad compost. Have you ever had experience with solarizing soil to eliminate a specific pest? The process has always looked cumbersome & iffy to me. Any cues toward a cure or a good experiment would be most welcome. :-)
I don't know what specific tomato leaf curl you have, but there is a newly arrived form in Australia regarding which this is a useful paper: This paper indicates that a white fly may carry the virus around. Here is a note on organic control of white fly
Hi folks, first post from me here in down under South Africa. I never put any decease plants in my compost. I will put weeds in a hot compost pile which kill the seeds. I have a question though regarding onion and citrus waste that is not supposed to go into a compost heap wether hot or cold I don't know and also if this is only applicable to earth worms in the pile. Any suggestions?
There’s more to home composting than leaves, grass clippings, and kitchen scraps. In a handful of brown-black matter exists an ecosystem of fungi, bacteria, enzymes, sugars, and nutrients. While millipedes, earthworms, and sow bugs make their way through the organic soup of garden refuse, it’s the unseen army of microscopic creatures that does most of the work of breaking rough stuff into compost. It’s that finished black gold and its benefits to our garden that we clearly see. A cold composting system is one in which organic waste is simply dumped in a pile to decompose. The gardener expends little or no energy managing the pile and just waits for it to decompose. Hot composting requires a system that raises temperatures high enough and for a long enough time to destroy weed seeds and plant pathogens. This requires some work on the part of the gardener, either up front with careful layering of materials, or later on with maintenance of pile temperatures. In between the two techniques are numerous degrees of intervention.
I recently invested in a tumbling composter and am doing some experiments to make a system that works the best for me. Initally I filled the tumbler with the remains of my old compost bin and added leaves, kitchen waste etc. I tumbled it amost every day and within a month it was looking quite broken down so I moved that into my old bin hoping to get the worms to move in and finish the job. My plan is to have that bin conintually being filled with almost matured compost, so that I can access it whenever I need it. I fill from the top and retrieve from the bottom (door). The tumbler works best when it is not being added to, so I have another bin where I collect kitchen scraps mixed in with shredded leaves so that they dont go slimy and smell. I have toyed with the idea of making a bokashi mix for this bin to start the breakdown process. As I understand it, collecting the material first is starting out cold, then once added to the tumbler, (and once the tumbler is full, nothing more is added) if it is tumbled once a day, then that should be hot composting. Once that is broken down and put into the bin to stand and mature it once again goes back to cold composting, where the worms do their bit. Any suggestions? Should I get a thermometer to make sure? I live in a hot tropical climate - far North Australia, so should it get hotter than most people in temperate climates reccomend?
Hello, I'm in Nowra, south of Sydney near the coast, different climate. But have in the past set up a permaculture garden in NT. Those rotating bins are best if filled entirely in one shot with lawn and green and chipped pruning materials, for a quick burn. Not a bad idea for preparation for on ground composting but should work on its own. Yes, turn every day or so. Up there you need no extra heat. Indeed, you have potential for simple sheet composting on the ground, also for burying kitchen waste, because the heat in air and ground means you don't have to worry about all the heating up, decomposition runs easily. Stay with the basic rule of 4 carbon (brown) to 1 nitrogen (green). Do you see many worms? Generally they do not like heat. Termites, though many may freak out at the mention of them, are major contributors to tropical soils. You might like to google 'soil tropical termites' to see some useful information. While people reasonably worry about termites attacking houses, they may be very pleased to have other food provided for them. This may interest you: .... I am now producing mountains of fine material for mulch and compost, reducing paper and cardboard waste to zero. The difference between sheet compost and mulch is in how fast it breaks down, which should really relate to what you are trying to do. A mulch is intended to inhibit growth of unwanted plants, whereas compost promotes growth. All good mulch should eventually break down and become a sheet of composted material. This will happen quickly in the tropics. And you can use this process, this shift over time, to enable you to manipulate who gets to make a good start in the garden.



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