How to Keep Compost "Hot" in Winter?

Question

I live in Pittsburgh (i.e., Zone 6) and I started a compost bin in the 2nd week in October. (I know, I should have started earlier...)

It has a lot of kitchen scraps, maybe 60-70%, but I've also been composting leaves, dead plants from the fall cleanup, and recently, spent paper tissues from our recent colds to get some more "carbons" in the pile. It's still probably really nitrogen-rich.

I add some warm water with each addition, probably 2-3 times per week, and have been stirring it with a shovel about once a week. About a week or two after starting, I added some "compost starter" from a local garden store to make sure it had enough good bacteria, and until this week it seemed to be making good progress and pretty warm.

But now, we're getting into winter weather, with lows (and highs) below freezing. What are some good ways to keep it going "hot" during the winter, or should I even worry? Ideally, I'd like to have this finished in April to May-ish, so I can amend the garden beds in the spring.

Answer 1

Practically speaking, a home compost pile is pretty much going to be stagnant through serious winter if your kitchen waste, etc is what's feeding it. I see the likely issue you'll have with "mostly kitchen waste" to be far too much nitrogen, but it won't help a home-scale pile get hot because the whole thing will be frozen. The "secret" to hot compost in the winter is "size" - I can pull up to the manure pile at the horsefarm, hack my way through 6" of frozen crust, and shovel a steaming-hot load into my truck. The vast majority of the LARGE pile is well insulated by the outer foot or so of the pile. In a 3-foot pile, that outer foot does not leave much pile to be insulated - if I leave the load in my truck too long, it freezes solid.

So, go big, or realize that composting in the winter on a small scale is basically storing frozen compost materials for the spring. I have thought about but never tried (expensive) some sort of insulated compost bin. Haybales or strawbales would be one way to give that a shot, and provide some material for future composting as well. But they might also turn into "rodent motel" (in the bales) right next to "rodent snackbar" (the pile.)

Answer 2

To keep compost hot, you need nitrogen content so leafy green materials need to be added to maintain the bacterial activity that gives off heat.

If you live in a Maritime or Southern climate where stuff grows year around, some of the lushest growth in certain weeds, clover, grasses and cover crops occurs in late fall and early spring so you can harvest it year around just about and keep the pile steaming fairly constantly.

Turn your pile and add a 1-2" layer of green material in between the compost layers.

Where it freezes in winter and growth stops, it's rather hard to accomplish adding nitrogen containing materials. If you're in a rural area, sometimes somebody else's horrific loss can be your gain, ie dampened alfalfa bales gone moldy or alfalfa floor sweepings are a really good nitrogen source for heating a pile.

Leaf piles are another environment altogether. Unless you shred them to add in thin layers to a hot pile, just pile them up and let fungal activity take its course. They need to be broken down by this means before they can be added to a hot pile anyway. Fungal growth occurs in cool environments so having the pile heat with undigested leaves kind of preserves them a bit longer than you'd wish.

One of the big issues with composting is maintaining the moisture level just right. Damp piles can go cold and anaerobic which releases nitrogen as ammonia. In my climate, I have to loosely tarp the pile to keep the rain out, snow melt probably doesn't help either.

Answer 3

This is my first time with a composter, and I just started it too with veggie garden waste; but I live in RI near the ocean, and we don't get many deep freezes here.I put a lidded trash barrel next to the composter with brown material in it: mostly peat moss. I add about 3 gallons of kitchen waste to the composter weekly, and add some of that brown on top of it; then mix it and check the moisture. In the scrap container, I layer the scraps with shredded paper. both to add brown and to absorb some of the moisture so the compostable trash bag does not begin to disintegrate. I have an 80 gallon plastic composter with a removable lid and front hatch for compost removal. I have never had any luck with composting in open bins before.