Compost Accessories: What Is Worth Buying

The one composting accessory that tells you something you cannot guess. A 20 inch stem reaches the core of a backyard pile, which is the only place the reading means anything.

Almost everything else on this page speeds up a process you could do by hand. A thermometer does something different: it tells you what is going on in the middle of the pile, which is information you cannot get any other way.

The numbers are worth knowing before you buy one. Colorado State University Extension puts the working range of plant-digesting microbes at 70 to 140°F, notes that a well-managed summer pile quickly reaches 120 to 130°F, and warns that above about 160°F the microbes themselves start dying. It also sets the bar for killing weed seeds and pathogens high: only a pile that heats above 145°F and is turned regularly does that reliably.

Those three thresholds turn a reading into an action. Cold means the pile is short of nitrogen, short of water or too small. Hot and climbing past 160 means turn it now to shed heat. Steady in the 120s to 140s means leave it alone, which is the most useful instruction a thermometer ever gives.

Stem length is the one specification to get right. Twenty inches reaches the core of the 3 x 3 x 3 ft pile Extension describes as the minimum size for heating. If your heap is bigger or deeper than that, the 36 inch version is the one to buy -- a reading taken near the surface tells you about the weather, not the compost.

Skip it if: you compost slowly in a bin and do not intend to manage the process. A thermometer is a tool for people who turn piles, not for people who fill a bin and wait.

Nothing moves a compost heap like a fork. If you have an open pile and room beside it, this is the tool that does the real work -- everything else on this page is a workaround for not owning one.

It feels wrong to put a garden fork in a roundup of composting accessories, and it is also the most honest recommendation on the page. Colorado State University Extension's own instruction is to fluff or turn the material with a pitchfork or aerator tool at regular intervals, and between those two, the fork does far more per minute.

A proper turn means moving the heap sideways into a second bay or a space beside it, so the dry outside material ends up in the middle and the hot middle ends up where the air is. Nothing you push down into a bin achieves that. It is also the fastest way to even out moisture, which is usually the real problem with a stalled pile.

Four forged tines with a fiberglass handle is the sensible specification. Wooden handles are nicer to hold and worse at being left against the bin in February. The Y grip gives you something to twist against when the material is matted.

If your compost is in a closed bin or a tumbler, skip it and buy an aerator instead -- a fork needs an open heap to be any use at all.

Skip it if: your compost lives in a sealed bin or a tumbler. A fork needs an open heap and space to throw material into.

The sensible tool for an enclosed bin: push it down through the material, and the wings open on the way back up to lift and loosen it.

Enclosed bins pose a problem the manuals gloss over: you are told to turn the contents, and there is no way to get a fork in there. Aerator tools exist to answer that.

The mechanism is simple and it works. The wings fold flat against the shaft as you push down through the material, then open as you pull back, lifting and parting the contents and leaving channels behind. Repeat it across the surface and you have introduced air without dismantling the bin.

Extension's position is that turning is not strictly required -- a pile will decompose without it -- but that turning speeds decomposition. An aerator is the low-effort version of that bargain: less thorough than a real turn, available in two minutes on a weekday evening, and therefore far more likely to actually happen.

Know its limit. A bin of fresh grass clippings compacts into a wet mat, and the wings will not open in it. That is a sign the mix needs more dry brown material rather than a sign the tool is faulty.

Skip it if: you have an open heap and somewhere to turn it. A garden fork moves far more material in the same time.

A corkscrew that winds down into compacted material instead of trying to punch through it -- the aerator to buy when the cheap one keeps jamming.

Wing aerators have one failure mode and it is predictable: dense, wet, matted material. The wings need somewhere to open, and a compacted layer of grass or sodden leaves does not provide it. A corkscrew has no such requirement -- it threads itself in.

That difference shows up most in bins that have been filled faster than they have been managed. Kitchen waste and lawn clippings compact under their own weight, exclude air and go sour, and a tool that can reach into that and open it up is the difference between rescuing the bin and starting again.

It is genuinely harder work than it looks. Winding an auger down into packed compost and hauling it back out again is a whole-body job. That is a fair trade for not emptying the bin, but it is not a gentle one.

Buy it second rather than first. If a basic wing aerator handles your bin, it is the right tool and this is money you do not need to spend. If you have already bent one, this is the upgrade.

Skip it if: a basic wing aerator already copes with your bin. This costs several times as much and solves a problem you may not have.

The cheapest way to make a pile useful before it is finished: screen out the lumps, use what falls through, and throw the rest back in.

Garden compost is never uniformly finished. The middle is dark and crumbly, the edges are still recognizable twigs, and the whole batch sits there looking like it needs another three months. Screening is how you get the finished part out now.

Mesh size decides what the compost is for. A quarter-inch screen gives you material for top-dressing beds and mulching, which is what most of it is used for. An eighth-inch screen gives something fine enough to blend into a potting or seed-starting mix, where lumps and sticks are a nuisance.

The oversize material is not waste. Everything that stays on the screen goes back into the bin, already colonized by the fungi and bacteria doing the work, which gives the next batch a head start. That is the free version of the compost starter two entries up.

Manage expectations on throughput. This is a bucket-scale tool, and screening enough compost to fill a raised bed would be a long weekend. For a few buckets to finish a seed mix or top off beds in spring, it is exactly right.

Skip it if: you spread compost as a rough mulch on beds. Unsifted compost is perfectly good on a raised bed -- sifting matters for seed mixes and fine top-dressing.

Useful as a nitrogen source for a pile made mostly of leaves -- and genuinely unnecessary for anything else, which is not what the category name implies.

This entry is here with a warning attached, because the honest answer is that most people reading about compost starters do not need one. Colorado State University Extension states it without hedging: compost starters or inoculums are not needed to start decomposition. The microbes arrive on the material and in the soil underneath it.

There is one situation where a product like this genuinely helps, and it is common in October. If your pile is nothing but fallen leaves, it is almost all carbon, and Extension's target ratio of roughly thirty parts carbon to one part nitrogen is nowhere in sight. A pile like that sits there for a year. Adding nitrogen gets it moving.

What it is, then, is a nitrogen supplement in a convenient granular form. That is a reasonable thing to buy if you have no grass clippings, no kitchen waste going to the pile, and no access to manure. It is a waste of money if you have any of those, because they do the same job for nothing.

If a pile is not heating, check the three likelier causes first: too dry, too small, or too much brown material. Extension's minimum size for a pile that heats is 3 x 3 x 3 ft, and the moisture target is damp but not soggy -- no more than a few drops when you squeeze a handful. Fix those before buying anything.

Skip it if: your pile already gets kitchen scraps, grass clippings or any other green material. Extension is clear that starters are not needed to begin decomposition.