still hot/steaming - can I use it?

ffreidlMay 24, 2010

Hi everyone,

I just got a truckload of mushroom compost delivered which I was planning to use for my raised beds. It looks great but turns out it's still hot to the touch. It was steaming as it came off the truck. Has stopped now, but I imagine it will start up again once the pile sits. It has a slightly sharp odor - not bad, but distinct.

Can I plant in this now or do I have to wait? If I have to wait, how long do you suppose it will be? Is it possible to use some of it mixed with something less active?

I do see some chunks that look like horse manure - I'm guessing they're really about 1/2 way to soil.


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It's a cache 22 because it sounds like you need to use the compost right now for your gardens; however, I'd highly recommend letting it sit and compost for at least another couple months (ideal world, right?). On top of that, I would reinoculate it using some cured compost, or compost tea. Most mushroom compost is sterilized (using steam) before it leaves the producer, so you'll want to reintroduce your beneficial microbes.

At the very least, it must be mixed 50:50 with your garden soil.


Here is a link that might be useful: Article on using mushroom compost.

    Bookmark   May 24, 2010 at 12:17PM
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I would not have let compost at this stage off my farm.

I would recommend one of a couple of things, let it mature to standards or incorporate (till) it into soil that will not be planted in for, I'm going to say, at least four weeks but that would be a WAG.


    Bookmark   May 24, 2010 at 8:42PM
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jbest123(Zone 5 PA)

The mushroom farm used steam to kill the spores. What you are seeing is normal and it will cool down in a few days once it is in the beds. John

Here is a link that might be useful: John's Journal

    Bookmark   May 25, 2010 at 4:56AM
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If this "compost" is still hot and has an odor that is sharp, pungent even if not very disagreable, and you can still see identifiable bits of manure it is not ready to go on your garden. Using it could cause the soil bacteria to tie up essential nutrients your plants will need to grow as the soil bacteria get to work on that "compost" to finish it.

    Bookmark   May 25, 2010 at 8:40AM
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Thanks everyone. Well, Dave has it nailed - I need it to fill my beds and without it I don't have any material. But I can see from everyone else's posts that my plants will likely be unhappy in there if planted anytime soon.

I'm fairly sure it's microbial activity, not steam processing, that's caused the heat - the pile has been moved and therefore mixed and is re-heating itself.

I'll try to let it sit as long as possible and mix in with other stuff. Would it make sense to try to fill the upper half of the beds with less active material while the still-cooking stuff goes in the bottom, so the roots can decide if/when they want to go there?

Or, perhaps the other way around, which might be similar to lasagna gardening?

Also, if mixing with non-active material, will this slow down or stop the decomposition in a way that will affect the beds badly for next year?

Your thoughts appreciated.

    Bookmark   May 25, 2010 at 9:32AM
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Now I'm really confused... Here's a discussion I just found:

I guess some people are planting in unfinished compost?

    Bookmark   May 25, 2010 at 9:51AM
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Here is another thread that sort of touches on this topic (there have been many just like this).

If the compost you have is still in the thermophilic stage, it's consuming a lot of oxygen. Reducing the oxygen consumption before using for small plants or seeds is a good idea.

Now I have a sort of related question, when people talk about planting in lasagna beds, are they planting seeds or plants that have a root ball of some kind already?


    Bookmark   May 25, 2010 at 12:32PM
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nygardener(z6 New York)

I'd let it sit until it's finished and either wait, or find something else for your beds. You can always use it later in the season.

    Bookmark   May 26, 2010 at 7:51PM
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It always makes me chuckle when I see the tumbler ads "Make compost in 14 days", or whatever. Then the non-commercial experts tell composters to let it sit for 30 days after it is finished.

    Bookmark   May 29, 2010 at 2:20PM
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jbest123(Zone 5 PA)

If that compost had any chance of heating up on its own, they would have never put it in the mushroom growing area. The mushroom spore is the most expensive part of growing them. I am not sure of the temperature but I think it is in the 80-90 deg range that the spore dies. John

Here is a link that might be useful: John's Journal

    Bookmark   May 29, 2010 at 3:26PM
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