Should You Use Sawdust as Fertilizer in Your Garden?

Sawdust as Fertilizer

If you ever made furniture for your home from wood or built a treehouse in the backyard, you most likely ended up with plenty of sawdust, and gathering them all in a pile can be an exhausting effort. But now, what do you do with the huge mound of sawdust? Can you or should you use it for your garden?

You can turn sawdust into compost and use it to fertilize the soil in your garden. However, sawdust takes months, sometimes years, to completely decompose. During that process, it absorbs plenty of nitrogen, which would kill your plants. Therefore, you should avoid using sawdust as fertilizer.

Sawdust can be either beneficial or utterly catastrophic depending on how you apply it. That is why in this article, we will go over how to properly utilize leftover sawdust for your garden and we will also cover some other topics that you should keep in mind when dealing with this material.


Is Sawdust a Good Fertilizer?

Sawdust consists of tiny wood particles that remain after sawing lumber. Just like trees, it has a high concentration of carbon, which is both good and bad for your garden.

Carbon is one of the main nutrients that plants of any species needs. This, along with hydrogen and oxygen, will make up the structural foundation for plants. So, the fact that sawdust is so rich in carbon should only be a good thing, and the abundant carbon supply will indeed be beneficial eventually.

However, a good fertilizer possesses another key element: nitrogen. The balance between nitrogen and carbon is crucial when choosing the right fertilizer for your garden. Of course, there also are other elements, such as potassium, ammonium, etc., although they’re not as significant as carbon and nitrogen.

Scientists have found that the ideal fertilizer should have a carbon-to-nitrogen ratio of 30:1, meaning the fertilizer you use should consist of thirty parts carbon and at least one part nitrogen. Otherwise, the fertilizer will fail to produce the results you seek.

Although this ratio varies depending on the species of plants and different soil types, the consensus is that nitrogen has to be a big part of the formula. Nitrogen is a key component in making chlorophyll, which is responsible for the photosynthesis process in plants and provides them a green color.

That is where the two-fold problem lies with sawdust. First of all, sawdust is practically devoid of nitrogen. It is mostly the remnants of the carbon skeleton of dead trees. But, this on its own would have been acceptable. You could have just turned it into carbon-rich compost and applied it.

However, the second aspect is more damaging for the plant’s life. Sawdust needs nitrogen itself to decompose properly. To be more specific, the microorganisms that will eventually break down the sawdust will consume a great deal of nitrogen from the environment. The greater the nitrogen supply, the quicker it will deteriorate.

Once fully decomposed, sawdust will have the same effects as any other naturally produced compost. It will make your soil more fertile and help retain moisture.

However, if you apply dry, raw sawdust directly onto your garden soil, you will face dire consequences. The nitrogen in the ground will deplete rapidly and your plants will soon feel the effects. The leaves will dry up, the branches will break off, and soon, the entire plant will die.

So, remember never to use dry sawdust in your garden. If you want to re-utilize leftover sawdust, always turn it into compost separately first.


Known to many gardeners as Black Gold, composting is a natural process of recycling organic matter, such as vegetable scraps and leaves, and turn them into a rich soil amendment. If you are new to composting, here are 10 things you can throw in your backyard composter


How to Use Sawdust in Your Garden?

From what we discussed, it is evident that sawdust on its own is not a good fertilizer. It does not possess the correct chemical balance you need for good fertilizers. But, you can still make good use of leftover sawdust if you have the patience for it. Just keep in mind that leaving that sawdust out and about can be hazardous.

Without further wait, here is how to simply turn sawdust into useful compost. If you worked on a project involving wood or have a sawmill near your residence, you will not have any problem collecting a ton of sawdust. Just make sure to keep it in one place to avoid making a mess.

Second, find a good spot to produce the compost. The place should be away from your home and the garden. It should also have plenty of air and sunlight and a cover to protect it from harsh weather.

Then, place all the sawdust in a pile and mix it with a nitrogenous substance. These substances include grass clippings, green leaves, coffee grounds, and vegetable and fruit scraps, to name a few. They will provide the nitrogen part for your compost. Next, add some water to keep the mixture wet, and thus, fasten the process.

From time to time, you can flip the mixture and move it around. This ensures that every part is receiving the same treatment.


How Long Does It Take for Sawdust to Decompose?

Sawdust typically takes a couple of years to fully disintegrate. This is, once again, due to the high carbon level and low quantity of nitrogen. To get the best results, you need plenty of nitrogen-rich materials for the composting process.

Sometimes, if the conditions are right, you can get useable compost within a year. Although, this depends on several factors. You have to get the ratio and moisture of the mixture right and ensure that there is adequate airflow.

The typical garden variety of earthworms can help in this process by eating and digesting the little wood shavings, which will accelerate the decomposition. So, if your garden has plenty of worms, it will be good news for you. Plus, earthworms are beneficial for your garden soil no matter what.


Things You Should Be Careful About While Using Sawdust

Never use chemically treated wood, such as plywood, finished wood, etc. These contain chemicals that can be fatal for your plants. You should ensure that the sawdust is completely natural and devoid of such chemicals. It is best to discuss the transaction with your supplier first.

You have to get the ratio of sawdust and nitrogenous substance right. Otherwise, it will not decompose properly and you will end up with a low-quality fertilizer.

Also, remember to keep the moisture right in the mixture, neither too dry nor too wet. The moisture will keep the wood shavings soft, making them more suitable for decomposition.

Finally, aerate the total mixture to promote better composting by the bacteria. You can do so by raking and moving the pile around. This will aid the addition of nitrogen, which is essential for the composting process.


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Can You Use Sawdust as Mulch?

Mulch is a gardening accessory that people use to preserve the moisture in the soil. The moisture level below the surface is pivotal for plants as it helps with the water supply and maintains a cool temperature.

Many people apply sawdust for this purpose alone. Usually, they will take dry sawdust and cover up the top layer of soil. Now, sawdust is very effective in preserving moisture thanks to its high carbon content.

But, you do have to be careful with this method. Indeed, if you add too much sawdust, it will rapidly drain the nitrogen in the soil for itself. Furthermore, the moisture preserving the nature of sawdust does attract termites and ants.

So, if are using sawdust as mulch, try to keep it to a minimum. Make sure that you are only applying it to the top layer of the soil and that no sawdust gets inside.

Additionally, the same property that makes dry sawdust lethal for plants is effective in killing weeds. So, this is another way to use sawdust in your garden. If you want to control the weed level or kill unnecessary plants, simply cover them with sawdust. Again, make sure you apply it away from the plants you actually like.


Does Sawdust Attract Animals?

Sawdust does have the potential to attract termites. Indeed, dry sawdust is effective in retaining moisture, which termites love. Therefore, a sawdust pile is ideal for a termite colony. Ants can also be attracted to sawdust, which could create a potential way for the termites to get inside your house and other parts of your property.

This is why you should keep the sawdust pile away from the house. If you notice a colony building up and infiltrating your home, use pesticide.



Sawdust is a common by-product of so many house projects and factories. So, to re-purpose it as fertilizer is an excellent, environment-friendly process. However, you should always be wary of the negative impacts of misused sawdust. If used without care, sawdust may bring more harm than good to your garden. 

As we have mentioned in this article, sawdust in its raw form is actually harmful to your plants. You need to compost it first before you can use it as a fertilizer. Another thing that you have to be aware of is the source of the sawdust. If it’s from treated wood, it should not be used anywhere in your garden.

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