Help with using a tumbler composter

DerffieJuly 12, 2014

This is my second year using a 50 gal tumbler composter. For a few months, I've been adding chopped kitchen vegetable "waste" alone with leaves that I piled up last year in a 1:3 ratio. In addition, I've added some blood meal and organic compost starter. I filled it about 1/2 way. It's been a week since I stopped adding matter. Doesn't smell bad. Reaches temps of only about 80 - 90 degrees, and looks OK but is quite wet. In fact, I guess as it decomposes, it seems to be getting wetter. I rotate the composter daily. I'm concerned about how wet it is (soggy) and the low temps. Suggestions? Thanks!

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I have a similar size tumbler, it does not heat up, not enough volume of material to generate substantial heat. Heat is not necessary so don't worry about the lack of heat.

Are you adding any kind of liquids? Dry leaves at the ratio you are talking about should not result in a high moisture situation. Is there precipitation getting in somehow?


    Bookmark   July 12, 2014 at 10:16PM
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Thanks very much, Lloyd. I have not added any liquid. It has been very rainy here but other than the ventilation holes on the side, I wouldn't think that the rain would be getting in. (I can test this using a hose once the compost is done.) It's reassuring to know that it doesn't heat up much. I presume, then, that it'll just take a while and I should just be relying on the quality of the compost to know when it's done. Would it make sense to dump it out on to a tarp to let it dry some?

    Bookmark   July 12, 2014 at 10:39PM
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I suppose you could but if it is not smelly I would not waste the effort. Adding some more dry leaves in small amounts might soak up some of the excess moisture. Because heat will not likely be a factor, having a higher C:N ratio is not going to be an issue.

At some point your tumbler will be full and it will need to just compost for a period. Do you have a second system to work with or is this your only composter?


    Bookmark   July 12, 2014 at 10:52PM
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I had similar problems when I started with my tumbler. The compost came out really wet and it never got hot. What I learned is for a HOT compost according to the Berkely model you need a 30:1 ratio. I never have that much dried material around so I use as much as I have and hope for the best. I often use shredded paper and that gets things hotter and it seems to suck some of the moisture out of the rest of the compost. I also read that I should turn the tumbler less often when I was sporting to get it hotter. It's another one of those balancing acts of getting enough oxygen to the microbes but also letting the interior get hot.

In summary, don't expect it to get really hot and add lots of dried material.

    Bookmark   July 13, 2014 at 12:09AM
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The minimum size composter that might allow the bacteria that digest the materials to work hard enough to generate the heat many look for is a 3 x 3 x 3, or 27 cubic foot, container or pile.
Often when kitchen waste is the primary source of material the moisture levels can become too great because of the high moisture content of that waste. Moisture excludes air that the digesting bacteria need to work, just as they need some moisture.
If a small volume composter is not filled full you also have even less volume for the bacteria to work on.
Perhaps this compost tutorial might be of some help.

Here is a link that might be useful: Composting Tutorial

    Bookmark   July 13, 2014 at 6:52AM
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The tumbler is currently my only system. I elected not to fill it completely because (a) it becomes quite heavy and difficult to turn, and (b) I was concerned that it would not get enough air. I too read about the 30:1, C:N ratio but didn't think that it was the same as brown:green. For example, "Let It Rot" lists leaves as 25:1 and yet we think of dried leaves as pure brown. I think I'll give it another week and then maybe add shredded paper as daragers suggests. This fall I intend to get my hands on a good chipper/mulcher so that I can have a large pile of leaves to use both for the tumbler and a pile. Thanks!

    Bookmark   July 13, 2014 at 7:50AM
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I kinda wish people would not focus on exact numbers. Thermophilic composting can be achieved when the parameters are in ranges. For example, C:N ratios. Sure 30:1 is considered to be optimum but a range of 25-40:1 is, for all practical purposes, just as good. Moisture can be in the 40-65 percent range. The optimum numbers are just that, optimum. They should not be thought of as being carved in stone.


Check out page 5 on the link. Note: this table lists the parameters for rapid composting, i.e. thermophilic. If one is not concerned with heat, the ranges could even be looser.

Here is a link that might be useful: Compost Management

    Bookmark   July 13, 2014 at 8:14AM
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tropical_thought(San Francisco)

One needs a curing bin after the tumbling stage has passed by.

    Bookmark   July 13, 2014 at 6:23PM
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I have a double tumbler--it is my second year. I am very happy with it. It certainly doesn't give me compost in 6 weeks like the store clerk said. It takes longer as I am constantly adding new materials, as the volume shrinks as it starts to break down. I am not afraid to fill it up full for that reason--it doesn't stay full long! Gives my arms exercise turning it!

I saw some steam the other day but mostly it doesn't get that hot. But it still breaks down nicely. One bin gives me more than a huge trash can full of compost. It takes months though.

I also have two vertical plastic bins that work nicely. I don't have enough material now to fill the two tall ones, so only one of them is working. I have a relatively small California yard, no room for a free large pile.

So, just wanted to add that you shouldn't worry about the temperature or even the amounts of green and brown. I use mainly grass clipping and leaves and flower deadheads, with coffee grounds and household waste (tiny amount) and shredded paper. I rarely add water as the grass clippings add moisture. I do get egg-sized balls of compost that I break up with gloves but I am sure you don't need to do that if you don't want.

Hope that helps.

    Bookmark   July 13, 2014 at 6:46PM
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tropical_thought(San Francisco)

This is what is wrong with tumblers, they cost too much and you need to have bins anyway. They are like expensive toys, but don't get down and dirty and give you a lot of compost, if that is your goal. If you goal is just to get rid of stuff, it's fine, but I like to have a lot of compost to use in the garden.

    Bookmark   July 13, 2014 at 9:05PM
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Indeed, that's very reassuring, kathy9norcal. I'm in Chicago where the winters can be arctic. Right now I"m using the tumbler more to avoid throwing kitchen waste into the garbage than to make large batches. I have started "helping" to make compost for our community garden. That is, no one else is doing it. They have three large bins. My thought is to collect leaves from the community, rent a shredder and create a huge pile for composting during the Spring and Summer. Most of their greens are fibrous roots, tomato plants and such. I've taken to chopping these with a sharpened transfer shovel. I can get spent hops from a local brewery and discarded produce from groceries as well.

    Bookmark   July 13, 2014 at 9:31PM
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nancyjane_gardener(Zone 8ish North of San Francisco in the "real" wine country)

Tropical- I bought my bullet type tumbler at the dump for $5....10 years ago! I add and add to this, and tumble 1-2x per week. After a few weeks, I dump it into a bin (I have 2 of these) to finish. I find it gets finished much faster than just adding to a bin!
OTOH, my hubby bought me one of those small crank tumblers and I have yet to figure out how to mount it above a bin in order to be able to dump into the finishing bin! Useless! (But I won't tell HIM! LOL)
I love my old tumbler (not so much the new!) but still end up dumping it all into a free standing bin! Nancy

    Bookmark   July 13, 2014 at 9:31PM
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tropical_thought(San Francisco)

That is a good idea about the winters, but they also make a closed system bin, but that costs a lot also. Compare the cost of bins vs. tumblers. If someone is just starting out, it's not good to spend a lot because you have to see if you will stick with it. If you are sticking with it and very devoted you can make any system work for you. The closed system bins will work in the winter, but I have never tried one or seen one even. I don't have real winters here.

    Bookmark   July 14, 2014 at 10:23AM
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