How Long Does it Take for Leaves to Decompose

How Long Does It Take for Leaves to Decompose?

In Gardening, Lawn & Garden by Jamie

Many plants and trees lose their leaves as the season’s change. This is a beautiful time of the year, but also a messy one. When all the leaves fall off the trees, how long will they stay there? Do you need to dispose of them, or can you just let nature take its’ course? How long does it take for leaves to decompose? 

Leaves left on their own to naturally decompose can take 1 year or longer; it depends on the type of leaf and its location. Although, you can decompose leaves yourself in 2 to 4 months in your own compost bin. 

First, let us talk briefly about the scientific process of decomposition, and then how you can use this process to your advantage.

What Causes Organic Matter to Decompose?

Organic matter decomposes due to bacteria. Bacteria present in the natural world eat and break down cast-off organic material like leaves, branches, and grass clippings. These bacteria, like all living things, require a certain environment to thrive. How closely the environment matches their preferred climate will affect decomposition speed.

The world around us is covered in a thin layer of this harmless bacteria. This bacterium has an important job – it keeps dead material from building up. When something like a plant or animal dies, this bacterium eats it and turns it into fertile dirt. This process is slow because the bacteria are so small, but some things decompose faster than others because they are easier for the bacteria to break down. Some examples of things that decompose quickly are leaves and grass clippings.

How Fast Will Leaves Decompose?

The rate at which leaves decompose can vary greatly but is usually between one month to a couple of years. When conditions are natural, decomposition usually takes one to three years. In conditions like composting, leaves may decompose in as little as one week.

What Factors Effect Decomposition Speed?

You may have noticed there is a large range for decomposition time. This is because several factors make a big difference in the way things decompose. Manipulating these factors is what humans do during composting as well as preserving food or making mummies. Below I will discuss the most important factors for decomposition speed.

Temperature

Several of the chemical reactions that bacteria use to reproduce themselves and break down organic matter happen more easily at higher temperatures. This means that the fastest decomposition occurs in warm environments. For example, a compost pile’s ideal temperature is about 60 degrees Celsius or 150 degrees Fahrenheit.

Moisture

Being either too wet or too dry will stop decomposition. This is because the bacteria responsible for decomposition require a balance of water, air, and temperature to live. It is ideal for decomposing material to be moist, but not wet.

Size

Larger objects take longer to decompose. This is because only the outside layer of the object is exposed to bacteria, and the inside will not rot until exposed. Therefore, a maple leaf will decompose more slowly than a bay leaf. The available surface area is small in comparison to the overall size.

Nutrient Availability

Important nutrients for decomposition are oxygen and nitrogen. These nutrients are provided by air circulation and the decomposing material itself. When organic material breaks down, it releases nitrogen. Some organic material is more nitrogen dense than others. The more nitrogen and oxygen available, the faster decomposition will usually occur. Unfortunately, this factor is difficult to manipulate. Everything has a fixed amount of nitrogen in it, and it is difficult to change that fact.

Factors Effect Decomposition Speed

Six Ideas to Speed Up Decomposition

We have just gone over what needs to be present for decomposition: heat, moisture, nutrients, and enough exposed surface material. Manipulating any of these conditions to be more favorable will drastically speed up decomposition. Here are five ideas on how to speed up decomposition.

Cover the Leaves with a Tarp

Covering something you want to decompose is an excellent way to speed up the process. It accomplishes several things. First, by covering the leaves you are protecting them from rain and snow, ensuring that they will never get soaked. Additionally, the tarp keeps the heat and moisture generated by the decomposition process from dissipating. This makes the pile moister and hotter.

Seed the Area with Finished Compost

As mentioned, decomposition relies upon bacteria eating the organic matter. This bacterium is likely to reach most organic matter left out in the open eventually, but we can help it by seeding the area with finished compost or dirt. Introducing finished compost (or dirt) to the leaves will introduce bacteria. This will kickstart the process and bypass the time it usually takes for bacteria to reach the leaves and propagate. When doing this you will notice a faster beginning to the decomposition process, but it will not increase the actual rate. To further speed up the process, this technique is best used in conjunction with others.

Spritz the Leaves with Water

If you live in a very dry place, you may want to occasionally spritz the leaves with water. Some moisture is required for decomposition. However, never soak the leaves, as this will cool them down and stop the decomposition process. I suggest this if your leaves are making no process at all, as too much or little water is usually the reason no decomposition takes place.

Shred or Mulch the Leaves

Shredding and Mulching are both ways to make the individual pieces of leaf smaller. This increases the surface area to volume ratio, which will make them decompose faster. As a rule, the smaller the object, the faster it will decompose.

Pile the Leaves in the Sun

The Sun will naturally warm the leaves and putting them in a pile will insulate the center, making it even hotter. The result is a significant boost in temperature which will speed up the decomposition process.

Put the Leaves on a Bed of Branches

Because the branches are stiffer and larger, they will provide a place for the leaves to rest while still allowing airflow through the bottom. This will ensure enough oxygen is circulating. Begin by making a mat of twigs or branches, leaving some holes. Then, pile the leaves on top.

Read Related: How Long Does It Take for Tree Branches to Decompose?

Related Questions

Will leaves decompose over the winter?

While leaves can decompose over the winter, they will not usually decompose as quickly as during summer. This is because many climates have wetter winters, and the lower temperature can inhibit bacteria growth.

How long does it take for a leaf to turn brown?

Leaves will turn brown when taken off the plant as they lose water. This takes between one to three weeks depending on the climate. Hotter climates cause leaves to go brown more quickly.

What makes a leaf turn brown?

Leaves turn brown when they become dry. This is a sign that the leaf is dead and cannot come back. Plants frequently section off parts of themselves to wither off and die, so one brown leaf does not mean a dead plant. It could however mean that the leaf was diseased, or that the plant does not receive enough water for its current size.

Will leaves decompose in water?

Because oxygen and airflow are required for decomposition, things do not decompose well underwater. When submerged, leaves may break apart but will not truly decompose into fertile ground. To encourage decomposition, leaves should be fished out of the water onto dry ground and put into piles.

How long does a tree take to decompose?

Depending on the size and conditions, a dead tree can take between fifty to two hundred years to decompose. Only the portions of the tree exposed to air can rot, so trees will decompose from the outside. Chipping or otherwise cutting up a tree will make it decompose faster.

Final Thoughts

When leaves build up each fall, we may wonder how to best dispose of them. Letting them decompose is an option, but without intervention, they will take several years to fully decompose. With techniques like tarping, seeding, and mulching leaves can decompose in a matter of a couple of weeks.

My personal go-to is a combination of techniques. I prefer piling the leaves on a bed of branches, seeding them with compost, and then covering the whole thing with a tarp. Mulching would also be a welcome addition to this system, although I do not often find it necessary. The leaves have usually decomposed before the next set of leaves falls.