Built a cubic metre pile in one go, mixed leaves and grass and some horse manure. It climbed to about 140F within 48 hours, held for three days, and then dropped to ambient over the next week. I've turned it twice since and it doesn't come back. Moisture feels about like a damp sponge. Is it finished already, or did something go wrong?
Check size and edges too. A cubic metre is about the minimum for holding heat and it loses it fast in cold or windy weather — the outer 20cm never really cooks. Turning outside-to-inside is the fix, and covering with a tarp or an old carpet keeps a surprising amount of heat in.
It's on an exposed corner of the garden and we've had a windy fortnight. Tarp going on this weekend.
"About like a damp sponge" is doing a lot of work. Actually squeeze a fistful from the middle, not the top. Piles dry out from the inside during the hot phase, sometimes dramatically, and a pile at 35% moisture looks fine and does nothing. If no water comes out when you squeeze hard, water it while turning rather than after.
One more thing, since horse manure is in the mix: if it came from a stable that isn't yours, be a bit careful about persistent herbicides in the hay. They survive composting and stunt tomatoes and beans badly. Grow a couple of bean seedlings in a pot of the finished compost before you spread it on a vegetable bed.
Lost an entire bed of tomatoes to this a few years ago. The bioassay with beans takes two weeks and would have saved me a whole season.
If it went cold it's done, spread it.
@compost_carl · 5mo ago · 3 replies
Nothing went wrong. That's what a hot pile does — it burns through the easily available nitrogen and sugars in a few days, the thermophilic organisms run out of food, and it cools. It is absolutely not finished, it's just moved into the slow phase where fungi and invertebrates do the rest over a few months.
A turn will usually give you a small bump, maybe to 100-110F for a day, if there's still fuel. If turning does nothing at all, the easy nitrogen is gone.
If you want it hot again you have to feed it: fresh grass clippings, more manure, or coffee grounds, mixed in properly rather than layered on top. Whether that's worth doing depends on whether you want speed or don't mind waiting.
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@root_rot_rhea · 5mo ago
Some people chase a second and third heat cycle by adding greens each turn. It works but it also means you're feeding the pile forever and it never finishes. At some point you have to let it just sit.
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@clay_soil_life · 5mo ago
That's reassuring. I'd read "hot composting" as though the pile should stay hot for weeks.
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