Using unfinished compost – Complete Guide




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Have you ever considered using unfinished compost on your garden? If you’ve emptied out your compost bin and you’ve got bits that haven’t finished composting, this is definitely tempting, but you must do so with care, because it can play havoc with your garden.

That’s why we’re looking at using unfinished compost – a complete guide.

You can use unfinished compost in your garden, but you should not put it on young plants, sensitive plants, or those that need a lot of nitrogen, or you may do quite a lot of damage.

Unfinished compost will strip the nitrogen out of the soil as it decomposes, and this can cause problems until the compost finishes decomposing.

What Is Unfinished Compost?

Unfinished compost is compost that still has visible bits of food or garden scraps in it, or compost that has not quite finished breaking down.

Essentially, it is any remaining organic matter that has not turned back into rich soil, but remains in its original form – whether that’s as a leaf, a seed, a piece of straw, etc.

Finished compost should be light brown, crumbly, and cold to the touch, whereas unfinished compost may be lumpy, darker in places, and is sometimes warm to the touch.

This warmth is because bacteria are breaking down the compost, and the process generates heat.

The bacteria will not be present in compost that has finished breaking down, so warmth is a sure sign that your compost is still decomposing, and isn’t ready for use yet.

Sometimes, it will be tricky to tell by sight. Unfinished compost might not have visible chunks of waste left over, but it could still be unfinished.

However, if there are no distinguishable parts, your compost is probably close to being ready, in which case it shouldn’t be harmful harm to add a little bit to your yard, so you don’t have to judge perfectly every single time.

Just make sure you aren’t adding a lot of unfinished compost, especially if it still has a long way to go.

Always check whether compost is ready before adding it to your yard, especially if you want to use it for seedlings or young plants.

If you can still distinguish any scraps of waste, those parts are not ready to go into the ground, and need further processing instead.

Why Might I Get Unfinished Compost?

Depending on your composting process, you may end up with unfinished compost when you empty your compost bin.

Unless you are running several bins at once, you are probably adding organic matter all the time, and at some point, you will want to harvest the finished compost for use in your garden.

This involves emptying the bin out, but you will then have lots of unfinished compost mixed in, unless you have started putting your food and garden waste elsewhere and allowed the bin to totally finish – which most people don’t have the space for.

At this point, you will end up with unfinished compost, and you may be wondering what to do with it. As mentioned, there are issues with just using this compost in your garden, so let’s look at that next.

What Issues Can Unfinished Compost Cause When It’s Used?

There are a couple of different problems associated with using unfinished compost in the garden.

Nitrogen Problems

The first problem that unfinished compost causes is nitrogen deficiency in the soil. The microbes that are breaking the compost down need nitrogen to function, and they will absorb lots of it from the surrounding area.

That means that the soil around unfinished compost will get stripped of its nitrogen, making this nutrient unavailable to any plants that are trying to grow there.

The plants may start to suffer from nitrogen deficiencies, which usually show up in yellowing leaves and wilting.

The nitrogen will be released again once the compost has been finished, but if you put lots of very unfinished compost in an area, this could take a long time, and may make plants very sick in the meantime.

You may have noticed that adding lots of nitrogen-rich ingredients to your compost bin makes it get very hot very quickly, and that’s because the microbes have plenty of nitrogen available and become extremely active.

Because they are so dependent on nitrogen, they will grab anything that they can from the nearby area, absorbing it and using it to generate energy so that they can keep breaking down the food and garden waste.

If you have added unfinished compost to the ground near plants, the best solution is to provide those plants with a nitrogen-rich fertilizer.

Keep an eye on them for signs of deficiencies, and add more fertilizer if necessary (but be careful not to over-fertilize, or you will run into other problems).

You may be able to remove some of the unfinished compost, which could be necessary if you have added a lot. Put it back in your compost bin for further processing, and then use it in the garden when it has finished.

Phytotoxicity Problems

Compost usually has a lot of different kinds of bacteria and sometimes fungi in it, which are playing roles in helping to break it down.

These vary depending on what you have included in the compost, but most will release amino acids as they break down the food and garden waste.

These acids will lower the compost’s pH and will remain in the compost until it becomes inactive because it has finished (this is sometimes called “cured”).

New compost can be very acidic, and these acids will damage nearby plants if the compost is used too soon.

Compost will gradually become more neutral after it has finished curing, and often compost is slightly alkaline, but unfinished compost will be acidic.

This acid can inhibit the germination of seeds and restrict root growth, even in established plants.

That means that you need to be very careful about using unfinished compost, because its acidity levels could hurt your plants. If you are going to be planting in your compost, it must be finished.

Equally, if you are digging it into the ground around your plants, it must be finished. If you use unfinished compost, your seeds will fail to germinate, and other plants may struggle, because the acid is harming them.

What Can You Safely Use Unfinished Compost For?

Bed Preparation Guide

You can use unfinished compost if you have beds that you want to prepare for the following year, especially if you lay it in the fall. Because of the issue it causes with nitrogen, it will even help to keep weeds at bay throughout the winter.

To do this, you should take your unfinished compost, and mark out the area that you wish to use it in. Spread the compost across this area, in a reasonably deep pile, and dig it into the ground.

You can also leave it on top, but be aware that it will take longer to wash in and break down.

Many people use unfinished compost across areas that they want to plant next season. Over the winter, the compost should continue breaking down, and hopefully it will be ready by the following spring.

However, you should remember that it will decompose much more slowly if it is spread over a wide area, rather than piled up. In a pile, the compost can get nice and hot, which helps to break it down more quickly.

Spread out across the ground, things will move far more slowly.

You shouldn’t put really “raw” compost out like this, because it probably won’t be ready for spring planting.

Midway decomposed compost should be okay, but don’t put any fresh food scraps down on flowerbeds or vegetable patches; they will attract pests and will not decompose in time for the new growing season.

If you aren’t sure that the compost has decomposed by planting time, do a soil test to see what the pH levels and nitrogen levels are like.

If the soil is still very acidic or the nitrogen is low, you may not be able to plant in that bed that year, or you might have to dig fresh compost in to help balance things out.

Mulching Guide

If you don’t have any new beds to plant into or you’re trying to use up unfinished compost during the growing season, you might be wondering what the other options for unfinished compost are.

You can use unfinished compost as a mulch around established plants as long as you do so carefully, and do not dig it into the ground. If you have large bushes, unfinished compost can be a useful mulch.

The mulch will help to keep water in the ground, which is very useful in the summer, especially if your area has water limits and drought problems.

You can use compost in this way by adding a thick two to three inch layer around established plants. Do not dig it in, but leave it on the soil’s surface.

This layer will keep water under the ground and ensure your plants have access to water for longer.

What Else Could You Do With Unfinished Compost?

If neither of those uses sounds appealing to you, what else can you do? The best thing to do is to allow your compost to finish composting, so you get a product that is easier to use effectively.

You can simply return unfinished compost to your compost bin, and use it to start your new compost pile. This might help to boost the new compost, because the partially finished compost is likely to be covered in beneficial bacteria, and may even have worms in it.

It is a good idea to empty out your compost bin, but don’t be afraid to put materials back. They don’t have a finite amount of time in the bin, and some stubborn ingredients may hang around for years before they decompose properly.

You will need to keep composting large sticks, bamboo, corn cobs, fruit pits, and nutshells for months or even longer.

Simply toss these things back into the bin with some nitrogen-rich ingredients (such as cut grass) and you will have your compost heap operating again very soon.

There is no reason not to simply give unfinished compost a longer run in the compost bin, and only use it when it turns into proper, finished compost.

If you don’t want to put the food waste back in your compost bin, consider something like trench gardening.

This involves digging a hole or trench, filling it with food, and covering it over again. It should be deep enough to hide the smell from rodents, etc.

How Can You Speed Up The Composting Process?

If you are struggling to keep your compost bin operating, there are a few things you can do to speed up the process and reduce the amount of unfinished compost that you are trying to deal with.

One) Greens to browns ratio. This is one of the most important aspects of getting your compost operating well. Nitrogen-rich ingredients (greens) will speed up your compost, but don’t add so many that it turns wet and slimy, or gets too hot.

Compost that gets hotter than 200 degrees F will not operate well, because at this point, the beneficial bacteria will die off.

Two) Moisture balance. Your compost should be wet enough to produce a few drops of moisture if you squeeze a handful, but not wetter or drier. If your compost bin dries out, water it lightly with a hose.

If it gets too wet, add lots of torn up cardboard to soak up the excess liquid.

Three) Cut up ingredients. Big chunks will take longer to break down, leaving you with unfinished compost. If you break things up before you add them to your compost, they will decompose faster.

Four) Stir the heap. Adding oxygen and mixing the ingredients is a great way to keep things moving quickly.


Unfinished compost can be used to prepare beds for the following year, or as mulch for established plants.

You shouldn’t use it for growing plants or seedlings in, but it does have a couple of uses in the garden, or it can be put back in the compost bin and further processed.

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