Is wood biodegradable? Can it be composted?

  • Date: May 13, 2022

Wooden objects can, most likely, be found in every room in every home across the country. Despite being an incredibly durable, unfortunately it will reach the end of its usable life at some point. If possible, donation of your wooden item to charity (or an up-cycler/crafter) is always our top choice. But if this is not an option, is wood biodegradable and can it be composted?

What is wood made from?

Knowing the origin of a material, and what it is made from, is a great start in determining if it can biodegrade. Wood plays a structural and protective role in plants and trees. Although composition varies between species type,  they are primarily composed of cellulose, lignin and hemicellulose.

So, is wood biodegradable?

An item is said to be biodegradable if it can be broken down naturally by micro-organisms such as bacteria. Wood comes from nature and can, essentially, return to nature. The process can take a minimum of a year – but it largely depends on the size of the piece of wood that is being broken down.

As with all biodegradable items, optimal conditions are extremely important. Many people think that landfill is just a big compost heap – unfortunately, this is not the case. Poor airflow and moisture levels make the breakdown process much slower than biodegradation figures quoted. Whenever you throw a biodegradable item in the trash it may still be around for a much longer time than you’d expect!

Is wood compostable?

Composting is a great way to cut down on household waste whilst producing a free, homemade nutrient-rich fertilizer. It should be no surprise that it is becoming more popular year-on-year. However, it is commonly thought that anything that biodegrades can be added to the compost pile. This is not the case – the terms ‘biodegradable’ and ‘compostable’ are not interchangeable. To be fit for the compost pile, an item needs to be able to contribute to the final nutrient-rich compost – whilst not contaminating the pile in any way. Thankfully, wood is both biodegradable and compostable.

Composting ingredients fits into two main categories: carbon-rich ‘browns’ and nitrogen-rich ‘greens’. Wood falls firmly in the ‘brown’ category. As you may know, you need an adequate mixture of the two types for a well-functioning, healthy compost pile. Too much carbon can lead to dryness and an ant infestation. Too much nitrogen, on the other hand, can cause excess heat and a slimy mess! To keep things straightforward, we often recommend a simple 1:1 ratio. Although you will see different ratio suggested elsewhere, this ratio works well and avoids any complicated math. However, even if you are stringently sticking to this ratio, you should always monitor the pile as you go along. No two compost piles the world over are identical – the ratio is merely a starting point. If you are new to composting, you can find some commonly asked beginners’ questions here.

Some considerations when composting wood…

You must consider what the wood has been previously used for before adding it to the compost pile. If it has been treated in any way, painted or varnished it could contain nasty chemicals that you do not want to contaminate your pile with. Burning it could release these into the air – so that is not a wise option either. If it is not suitable for donation, unfortunately, the best place to take is your local refuse center.

Like other compostable items, you can speed up the process by cutting the wood into smaller pieces. The smaller the pieces are, the quicker the breakdown process. Wood chips will be fertilizer far quicker than a tree limb, for instance. As well as providing a larger surface area for the microbes to act on, it also means you can mix it throughout the pile. This is not absolutely essentially – but it is highly recommended. You could be waiting decades otherwise!

The bottom line

Although it can take a significant amount of time to compost wood, it will eventually break down and form a great nutrient-rich compost. This will ultimately benefit both your garden and the planet. Although composting is an environmentally friendly way to dispose of waste, we recommend that you consider donating your item first if possible. Lots of resources have been put into its production – maximizing its lifetime is always the first option to consider.