7 Reasons why your compost heap is taking longer than expected




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More and more people are getting into home composting as being a great way to deal with organic waste and go a little greener, and that’s a fantastic thing – but sometimes, compost can be a bit confusing or frustrating.

It may surprise you how long it takes for food to compost, so today we’re going to look at 7 reasons why your compost heap is taking longer than expected.

The top reasons that compost may take a while to finish decomposing include being too cold, too wet or dry, or too compacted.

Your compost depends on bacteria and worms in order to decompose properly, and if something happens to upset the balance, these may leave or die off – and then your compost heap will stop operating, or will only work very slowly.

One: It’s Too Cold

Compost depends on heat to work properly, and cold compost is not operating at maximum efficiency. Warm compost is more hospitable to the bacteria that are needed to break down the organic matter.

These bacteria generate heat themselves, but they are less likely to be active in a cold compost pile.

person turning a compost heap

If the compost is too cold, you can warm it up by turning it regularly. This will encourage the bacteria to start working because it increases the oxygen flow, and they will generate heat, which should encourage more bacteria.

You can also try hot composting if you purchase a specific bin. Even just stirring and lifting your compost once or twice a week will help to boost the warmth in there.

Two: It’s Too Wet

If you have a compost bin that is exposed to the elements or you have added a lot of wet ingredients to your compost lately, you will probably notice it getting very wet.

When it’s too wet, compost can’t work properly, because the worms will leave (rather than drown) and the aerobic bacteria will suffocate because the water drives out the oxygen.

Your compost will often get wet if your balance of greens and browns is skewed. Green material is “wet” stuff like food waste, green garden clippings, etc. Brown material is straw, dry leaves, cardboard, etc.

Compost needs a mixture of these two things to operate properly. If you haven’t added any shredded paper, eggshells, nutshells, twigs, or other carbon-rich “brown” ingredients lately, your compost heap may turn wet and sludgy.

This will usually be accompanied by an unpleasant smell, released by anaerobic bacteria (because there is no longer oxygen in the pile) and your compost will stop working effectively. It will start rotting, rather than breaking down.

You can fix this by turning the pile and adding lots of brown materials to soak up the excess moisture and give the pile more structure.

person holding very dry compost

Three: It’s Too Dry

Equally, a compost bin that does not have enough green ingredients and has too much carbon in it will not work well.

The bacteria and worms do need some moisture, and if your compost pile dries up completely, it won’t do anything at all for months at a time. This is even worse than too wet in some ways.

You should try to correct this by adding some greens to your compost bin, or lightly watering it with your hose. You can add food waste, garden clippings (green leaves, weeds, etc.), or cut grass in small quantities.

Make sure you stir your addition into the pile so it can do its job and make the compost wetter.

If you are having a dry spell and no rain is due for a while, you may wish to add to this strategy by lightly watering the compost pile to increase the moisture level, but don’t overdo this or you’ll encounter the opposite issue!

Dry compost should be reasonably easy to deal with, but you do need to correct the balance in order to get it operating efficiently again.

You are much more likely to have a problem with dry compost if you have recently cleared twiggy, woody parts of your garden, or added a large quantity of straw for any reason.

Dry compost often won’t smell bad (because it’s essentially inactive and isn’t rotting or composting or really doing anything) so you might not notice straight away.

The best way to tell if the moisture balance is right in your compost bin is to pick up a handful of compost and lightly squeeze.You should get a few drops of moisture on your hand, but it shouldn’t be dripping.

If there is no moisture, you need to add some wet ingredients or water; if there is too much, add some dry ingredients and turn the heap to help it dry out.

mix of compacted vegetable compost

Four: It’s Too Compacted

Sometimes, your compost bin will stop working because it has got compacted. If you have added a lot of ingredients, especially heavy ones, to the top of the pile and you haven’t turned it for quite a while, this is a relatively likely explanation.

Compacted compost cannot decompose properly because there is no air at the center of the heap, and the bacteria is therefore unable to do its job.

If you have lots of worms in your compost heap, they may help with this by digging tunnels that add oxygen to the heap, but you may also have to take steps yourself.

You should take a garden fork and turn your compost heap regularly. This will keep the bacteria active, mix the materials, and prevent compaction. If you find it difficult to turn the heap, try just pushing a fork in and wriggling it around in several different places.

This will add at least a few holes to the heap, allowing air to flow through it. It is not as effective as turning, but it will help solve the issue and break up the compaction. With any luck, the worms and bacteria will do the rest.

Five: It’s Too Hot

This is a rarer problem, but you may occasionally encounter it, especially in summer, with large compost heaps that have a lot of material added to them.

Although hot compost is usually a good thing, if you let your compost get too hot, the worms will leave and the bacteria will die. This will quickly cool the heap.

It will usually restart on its own, but it may not do so, and this will still slow the process down considerably – which may make your compost take longer than expected.

If your compost gets over 200 degrees F, it is too hot and the organisms that are responsible for turning the organic waste into compost will quickly leave it. There is also a slight risk that the heap could catch fire, although this is rare with backyard compost heaps, and usually only happens with massive commercial ones.

If you think your compost is too hot, measure it with a thermometer. You can then do a few things to decrease the temperature.

Start by spreading the pile out and dividing it into smaller heaps (allowing heat to dissipate at the same time). Smaller piles cannot trap as much heat, and will usually not reach temperatures of 200 degrees F.

If you’re still having problems, check your balance of greens and browns. Too much nitrogen can cause a heap to heat up very fast, so reduce the amount of greenery you are adding a bit.

person emptying grass clippings into green plastic bin

Six: It Has Too Much Grass In It

While grass is a great thing to add to your compost heap, too much can cause issues, and this is a common problem for home compost bins. It might be tempting to empty your lawnmower’s basket into the compost, but you should do so with care if you have a large lawn or a small heap.

Your compost bin can only handle so much nitrogen at once, and grass tends to mat and compact, which makes it harder for the worms and bacteria to deal with. It may also disrupt the airflow or increase the temperature.

It’s best to add grass in small quantities and stir it in thoroughly to reduce the chances of it causing problems in the bin.

Seven: The Material Is Too Large

Another possible reason for your compost taking too long is that you are adding big chunks of material. The larger a piece of organic waste is, the longer it will take to break down, especially if it is fibrous.You can solve this problem by cutting up your compost ingredients before you add them to the bin.

You don’t need to bother with soft ingredients, but if you have things like corn cobs, brambles, sticks, and other fibrous material, chopping them first can really speed up the decomposition process.

It also makes it easier to turn your compost, meaning the pile will be more active and will operate more efficiently.


There are quite a few things that could be slowing your compost heap down, but hopefully you now know what to look out for and what to do to fix some of the common problems you might encounter.

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