What you propose will certainly get warm. Was there a specific question?

i guess i am looking to see if anyone has a "recipe" that they really like for using UCG, especially at a time of year (i am in the NE) when leaves and other browns are scarce. i did not plan ahead for composting, obviously, and i am scavenging for materials, but in future i'd like to develop a go-to.

If I understand correctly, UCG is just coffee grounds. So call it that. Just about everyone uses coffee grounds for composting. It'll probably compost all by itself. You want a recipe that doesn't use what most people use. If you're insistent about adding carbon, then maybe just shred some newspapers. You should be able to lay your hands on loads of that.

Plus to newspapers you could visit Aldi store, they have lots of packing boxes free to take. Also, BJ's club, or similar stores have them of free. When we are shopping, my spouse takes groceries, I shop for boxes there. :))) But, of course, you need a good shredder , which will eat thick cardboard without problem.

If you want to heat up an inactive pile, just add N - in this case the coffee grounds alone. Adding in 'browns' (the C source) will offset the effect of the N and pretty much neutralize the effect.......no heat generated. OTOH, if the pile is very wet you may want to add some paper, straw, cardboard, etc. as well to dry things out but keep the percentage of N high. I would do a 1:1 rather than a 3:1 ratio.

btw, UCG is a pretty standard acronym for coffee grounds used in all manner of writings and publications. Stands for Used Coffee Grounds (as opposed to unused ones!)

Hmm. Never heard that acronym. But I guess it's for real. I don't like to talk in acronyms, when real words will do. IMHO KWIM? JSYK.

Shredding cardboard is a pain. But newsprint is easy and, as long as it doesn't compact into a slab, will do nicely.

Adding browns certainly won't neutralize anything, and the compost pile will still heat up. Just not as hot. You will have more compost. I compost dry fallen leaves all by themselves and they get wicked hot.

As noted, however, coffee grounds have a C/N=20, which is pretty much optimal for a compost pile. If you can get loads of coffee grounds, why bother with anything else?

Spent coffee grounds would need constant turning in order to keep it oxygen fed. Did you mulch the straw before making your pile?

Good point. A pile of coffee grounds would compost like a pile of sawdust. Mostly anaerobically.

What size is this compost pile? It is difficult to get compost with a volume much less than 27 cubic feet (a 3 x 3 x 3 pile) to heat up.

I think floral)_uk is on the most important track here. what's the issue / what do you want? If I had access to large amounts of coffee grounds - within reason - I'd probably dump them on my yard/lawn or under trees, rake 'em so that they're not too thick or noticeable, and forget about 'em. They'd be indistinguishable from soil / dirt pretty quickly anyway. I don't have any straw so I wouldn't go out of my way to get any. But I'm not trying to give recommendations here, I just don't understand what problem you're trying to solve.

The purpose was clearly stated in the initial post - the OP needs to 'heat up' a small, inactive pile. Reactivating a dormant or cold pile requires N, hence the use of the coffee grounds (or some other strong N source).

A good point is made with the size of the pile however - small piles seldom gain and maintain adequate heat to decompose efficiently, which is why most tumbler systems do not work very well.

Heat it up why?

If the purpose was to heat up a small compost pile, and the OP has plenty of coffee grounds, the answer is, um, dig them in! If you want a recipe for digging, we can probably come up with something. Compost doesn't need a "recipe". It needs organic matter, moisture, and time. By "heat up", I assume the OP means "accelerate". Nitrogen containing materials will do that. A cold pile can compost quite adequately, but it will just take more time.

Composting isn't an art form.

Heat is the most efficient decomposition element. Heat does accelerate the process, resulting in finished compost faster. And it also has the added benefit - if sufficiently high temperatures are achieved and maintained - of killing off weed seeds and pathogens.

Heating up your compost.

I'm not sure the OP's purpose was clearly stated. It seems ambiguous to me since my understanding was that the OP was building a heap using only UCG and straw and wanted to know how to get it to heat up. Not that the UCG and straw were a mixture intended to heat up an existing heap which is GG's interpretation as far as I understand it.

Yeah, I read the opening statement to be a a little, unintentionally, ambiguous.

If the goal is to heat up an old pile, then - if it isn't finished - just toss the grounds in there and stir. The 'cold' pile will have plenty of 'browns' already. Depending on how old, or its consistency, I'd think about sifting it first, remove anything finished, then build a new pile with the UCG and the unfinished remnants of the old pile.

If the idea is to build a small pile from scratch following a recipe using UCG, and a material like straw, it's not easy to get anything less than 3' X 3' to 'heat' up. It will decompose eventually, but...

Years ago, it was common to make a hot frame for spring and mild-winter gardening. A hole was dug, and fresh manure (sometimes along with urine-soaked straw bedding) was tossed in and buried with soil. A cold frame was put on top. Plants were grown in the frame above the decomposing manure. You don't need as much fresh manure to produce heat as you do other materials. The soil would stay warm enough to grow cool-weather crops. In a greenhouse, the same basic method was used, but A LOT more manure was needed.

In any case, I don't think you're gonna get coffee grounds to heat up like manure would.

As others have said, knowing the purpose would help. Myself, I put UCG right into the garden. Their texture and size makes my clay a bit more friable, and the worms 'go to town' quite quickly.

Let's forget about killing off weed seeds and pathogens. We're talking about a "small compost pile", and such piles simply won't heat up enough to do that effectively. Heat is a byproduct of decomposition. It doesn't do the decomposition. If you heat up a sterile bed, NOTHING will happen. So much for heat being an efficient decomposition element. Yes bacterial action can be accelerated by heat, but that bacterial action makes its own heat. So yes, a hot pile is fast. But not because its hot. It's because there is a lot of bacterial activity going on, digesting hydrocarbons.

Maybe the OP will reappear, but it was clear to me that what was desired was to get a small compost pile cranking. The ingredients to do that were available. Case closed.

Well, we are getting a little unnecessarily pedantic here! I know how heat is generated or works in a compost but opted not to complicate the issue (which appears to be confusing to most) by explaining it in more detailed scientific terms. Suffice it to say that heat and decomposition go together, which is the answer to "Heat it up why?". Even a cold compost will generate heat but never to the same degree that an actively maintained pile will.

And an optimally sized 3'x3'x3' pile that is properly maintained and activated will indeed generate sufficient heat to kill off weed seeds and pathogens. We frequently see comments on this forum to that effect, with folk measuring temps as high as 160F.

It isn't a detailed scientific explanation to say that bacteria, when munching, get hot, and heat doesn't make bacteria munch. But many people say that heat does the work in a compost pile. It simply doesn't. There, that wasn't complicated.

I get 150F inside my 3x3x3 pile, and that kills stuff in the middle of the pile. But it doesn't kill stuff on the periphery, and when that peripheral material is turned in, the pile simply doesn't get as hot, because a lot of the fuel is consumed already, and the fuel base is diluted. A large enough pile can be turned to expose all of it to high heat. What makes a large pile hot, even when fuel levels are low, is insulation. LOTS of insulation.

If you're composting meat or fresh manure, with potential pathogens, in a small pile, I'd be very careful.

OP here. simple goal: approx 4x2x2 hotbed in my small, unheated greenhouse for bottom heat/seed starting. given that i did not plan ahead for this in the fall, my stockpile of leaves and fall cleanup is currently buried under approximately 25" of snow. trying to use what i have on hand to get a pile going: unlimited Used Coffee Grounds; shredded hay and straw from local farm; all of the recyclable office paper my office can supply, including cardboard and newsprint; VERY limited supply of kitchen waste. i am NOT planning on using this particular pile in the yard given the hay and the seedhead issue, though i may use a small solar oven later in the spring to see what i can do With Respect To that particular problem. (and also, of course, depending on how hot the hotbed pile gets)

my ONLY concern right now is experimenting and trying to get this hotbed/bottom heat concept cranking, and i want to keep it simple with the two "ingredients" i currently have the easiest access to. (to recap: hay/straw mix and UCG) i consulted You Bet Your Garden - they have a great post on this - and a local farm here in the hudson valley. (http://www.hvgardenjournal.com/2013/07/16/event-photos-compost-heated-greenhouse-tour/) her ratio was approximately 2/3 UCG and 1/3 brown yard waste.

to restate my original question: given these two immediately-accessible ingredients, what ratio would recommend? i am starting with 2 part UCG to 3 parts "brown" straw/hay just given what i have this moment.

I think the issue here is that quantitative recipes really aren't that important. You need some "greens". You got 'em. The coffee grounds. You need some "browns". You got 'em. The remains of your old pile, and whatever else you want to throw on. Recipes are derived by people who desperately want to optimize and who have analyzed their inputs with great precision. You have not done the latter. Most of us don't care a lot about "optimization". We just want compost. There is no mistake possible here. You'll get compost however you combine them. 2/3 is fine. 1/2 is fine, 1/5 is fine. My recommendation? Get out your shovel and start digging.

In that article, they used 2 parts UCG, and 1 part "city collected leaves or chipped yard waste." If you look at the pictures, the woman is building the pile inside concrete blocks that come up to her waistline. That's at least 3' tall, and probably at least 2 1/2' - 3' wide, and 3' - 4' long. So, to get their results, you're looking at at least a 1 cu. yd. size compost pile. That's not really what most here would define as 'small'. It's quite average for a working compost pile.

"Small' often conjures images of a tumbler-sized amount.

I think it's a good idea. It uses the old methods, and common waste from modern living.

OK - the goal may sound 'simple' but it wasn't explained very clearly. The original post didn't mention that this was to be a hotbed in a greenhouse and its sole purpose was heat, not decomposition. A hotbed is an entirely different animal from a common or garden compost heap. I've never read any accounts of hotbeds that use anything other than strawy manure. You need to be researching hotbeds, not compost making. If you can get it to work report back. You may be doing pioneering work. (I don't think peeing on it would do any harm. Worth a try.)

Sometimes 'why' does make a difference. Some want it to get hot to speed things up, some to kill weed seeds, some want for very specific reasons like here, and some think they have to get it hot because Big Compost (joke) told them so. If you just want to use coffee grounds in the garden, you can do worse than just spreading them around.

Separate note: as rgreen notes, in the video they used city-collected leaves (often has grass and other) and chipped yard waste, both of which may contain a fair amount of greens to start with. I've not used lots of coffee grounds but I've never found they contribute much to a pile heating up - but YMMV, and coffee grounds may come in different varieties.

My apologies. I didn't read your last post carefully. So this is a HOTBED. That certainly wasn't evident from the OP. Many people want to heat up their compost pile for various reasons relating to compost. Seems that what you need depends a lot on what temperatures you're trying to achieve, and what outside temperatures you're trying to fight. For a 4x2 area, I'd have to believe that an electrical heater is a far more controllable and reliable option. Is there some reason that you need a hotbed? Maybe you don't have power in your greenhouse?

I don't know much about hotbeds, but compost piles get warm mostly because of the insulation. If you flatten out the pile to fill an area, I'm sure it won't get very warm. I mean, my mulch layers are sitting on the ground composting, and they sure aren't getting warm.

I was searching around on that blog and found a second post on the subject... Heat a greenhouse with compost, even in the city!

It says... "Each bay holds about 1.25 cubic yards of compost materials, a layer of
cardboard and a layer of clean mulch goes on top and then the soil."

To actually 'heat' the greenhouse, there are multiple bays that combine to heat the larger space. It goes on to say that in the winter, the air 'may hover around freezing', but the soil stays warm. There are additional techniques (plastic hoops with thicker row covers for example) that could be used in the coldest of days, but many plants that can be grown in cool conditions really just need their roots to stay above freezing.

my greenhouse is 6x8, on an east-west axis, not heated, and does not have power.

there's no reason i "have" to, it is something i stumbled across while doing some googling, and it sounded like an experiment worth undertaking. i have a more traditional indoor light system, but it seemed like a waste to not investigate a way to get bottom heat and get a few weeks' jump on the season in my greenhouse.

i am currently building a bay not unlike the setup in the blog post referenced above; i anticipate it will be about waist-high, 2ft deep, and about 60" long. i have the cinder blocks from a construction project on my property, free coffee grounds, free straw/hay, and free shredded paper. (in a few weeks i will have a nearly endless supply of dried leaves from the few acres' woodland i have.)

while doing research on the concept late last week i found that it's hardly a new technique - as others have noted, hotbed gardens date back to at least victorian england - but there are some few others i've found that have built them in their unheated greenhouses to good effect. even someone here on gardenweb. (especially a comment on this thread, pretty far down, from bev, who includes photos from her greenhouse hotbed and says "So far so good. Plants on the hotbed and bin have come through minus 7 C nights with no problem. The rest of the greenhouse frosts up but everything over the hotbeds is just fine.")

i plan on supplementing this with reemay, etc, as appropriate, and of course i am not planning on starting tomatoes tomorrow. just trying to get a few weeks' jump for my annual bedding plants (i.e., i start several hundred nasturtiums for my various outdoor beds, same thing for zinnias and cosmos) and maybe getting a few extra weeks out of my melons so that i can get a crop from something other than minnesota midgets. i am hoping to have a pile "cooking" by the middle of april or so.

FWIW i am in zone 5b/6a, though this winter the temperatures have been hovering in zone 7 territory, with a few nights that hit single digits, nothing zero or below (F). even this coming week, with the protection added by the greenhouse, temperatures won't dip below freezing.

I've used wheat straw as a brown exclusively and have been disappointed every time. I'd get a very brief heating event and then nothing. Straw does not have a lot of readily available C to sustain thermophillic composting for an extended time. Now this wasn't with UCGs exclusively (mostly fresh grass clippings) but there were UCGs in it. It composted well enough over the long term in that I eventually got decent 'post, but no where near as good as leaves. If you are looking for heat, a long period, and aerobic activity, straw is not the answer IMO.

The classic bottom heat hotbed, for a pineapple house or growing melons or starting seeds, used a LOT of fresh horse manure and table bedding (high nitrogen and high carbon) in beds 3 or so feet deep.

Something as small as yours will have a hard time maintaining heat for long.

Straw has a lot of lignin, and it's not as easy for the bacteria to use as a carbon source as leaves.