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Why Is My Compost Going Green?

Every year it seems like there is a new compost-related topic, and as I take a few moments to enjoy nature, I remember someone’s concern online about the greening of their compost. 

You’re probably throwing your scraps and yard trimmings into a bin and letting it sit for around two weeks. Then, you’re ready for your compost bin only to realize it has gone from brown to green.

What’s the cause of a green topping or lay occurring out of nowhere? Your compost is going green because algae and mold.

If you notice a difference in the color of your compost, it’s time to get a closer look. 

The reason is the compost is exposed to the unwanted elements. 

If this is the case, you should take control of your compost pile.

If you already have a compost pile that looks unappealing, this article will show you why and how to make your compost look fresh by getting rid of the greenish mess.

Why is my compost turning green?

When you have a compost pile, most of the time it should be brown and at the bottom. 

This is the case when you’ve added proper amounts of green stuff, like grass clippings, coffee grounds, and egg shells. 

However, if it starts to turn greenish. There’s a chance you’re dealing with algae or mold. 

What is algae?

Of all the plants that can be grown in your yard, algae is one of the most fascinating.

Algae is a general term to describe a group of single-celled green plants that live in fresh and saltwater.  

Algae is a type of plant that contains chlorophyll. 

This plant uses sunlight to produce energy and is photosynthetic. 

Algae is an aquatic plant and needs to be in water to survive.

Algae and other microorganisms can be used as a source of food for humans and other animals, but not all algae should be consumed by humans.

They are able to compete with other living plants by producing natural toxins, and reproduce through sexual reproduction or budding.

Why algae thrives in the compost

Compost is a great way to improve soil conditions, help reduce odors and control plant pests, but whether or not it’s your friend depends on the microorganisms that live in the pile. 

In the case of commercial compost, many of the organisms that live in these piles are not native to the soil. 

Analyzing compost piles for signs of algae is an easy way to determine if the compost pile you use at home is performing as it should.

Most of us have seen it at some point: a small, green, scurrying creature that lives in our compost bin. 

Though it is hard to keep up with what your compost bin has become, you can still be sure that a great deal of that compost—made up of worms, small animals, and even some fruits and vegetables—has been made up of their bodies.

Everyone knows that compost drives beneficial microorganisms, including fungi, bacteria, and protozoa, to work in the compost pile and decompose most dead organic matter into nutrients that are easily assimilated by plants. 

As such, compost contains chemicals such as nitrogen, phosphorus, and potassium that can feed the algae. 

Other reasons include: placing too much manure in the pile or using too much nitrogen-rich manure.

How algae spread in your garden

Algae that reproduce both sexually and asexually.

Some use cell division to multiply. 

Like plants, other algae reproduce asexually by spawning spores which drift through the air and water.

If you have ever had areas of your garden where the grass is dead and the dirt is covered with thick green patches of algae, you know how devastating this can be.

That dirty little green stuff that grows all over your pool’s filter and docks show no signs of going away. 

Yes, algae, you may not be able to see it, but it’s still in your backyard. 

Maybe you started with a handful of green and crunchy algae and over time you have a bunch of slimy, slippery algae.

Unfortunately, not all of the world’s water is clean and algae will grow in dirty water. 

When this happens, algae can easily spread into our soil.

In addition, many people fail to realize that algae can be introduced to their garden from outside sources. 

For example, if you get an algaic soil sample from a local garden center, it is likely that you will find the algae growing in that soil.

Will algae harm your garden?

Your lawn is important. 

It’s the first thing that catches the eye of a visitor and often the first thing that gets a person to stop and glance at your home. 

But lawn is also a common weed and plant problem in residential landscapes. 

You may not recognize the plant, but it’s the same one that’s causing your lawn to turn brown and die, and it’s the same thing you see in your neighbor’s lawn. 

The culprit? 


Algae is an inexorable scourge of all gardens, ponds, and fish tanks. 

It can clog up water filters, choke out fish, and gum up plants.

What’s even worse, they’ll compete for nutrients leaving your plants with little chance to fight for their survival. 

When algae continue to thrive in the garden, they can take in a lot of moisture and harbour other diseases and mold. 

How to get rid of algae in the compost

Composting is a great way to recycle food scraps and garden detritus into rich soil.

Anywhere you can put your waste, you can compost it, but there are some things you need to pay attention to such as the emergence of algae.

Does algae in your compost stink? 

Some types of algae can wreak havoc when they end up in your garden.

There’s no doubt about it, we’ve all been there: we’ve spent hours trying to get rid of the algae that may be lingering in our little pond or fountain, and failed miserably. 

The good news is that it’s not a big deal, and there are solutions to prevent algae from taking over your compost pile.

1. Drain excess moisture

Algae on a compost heap is not a pleasant sight, but don’t be too quick to blame the compost. 

Algae grows on ponds, lakes and even the ocean, so it’s not uncommon to see algae on compost heaps too.

If you have a pond or a garden, you may have already experienced algae. 

When you add a compost heap to your garden or outdoor space, you’ll notice algae forming on it within a week.

You need to periodically remove the water from the pile so the algae can’t grow as much.

Compost that’s too wet provides breeding ground for algae.

Use compost bins with holes to allow excess moisture to drain away.

2. Bury the compost

Dumping the same materials in the same bin over and over again will promote disease and result in a slimy, smelly mess.

To get rid of algae in your compost, you need to limit the supply of carbon dioxide to it, by burying it deeper than the usual half inch recommended by most gardening books. 

One way to get rid of algae without using chemicals, and one of the most effective is by burying your compost in a trench.

If you can bury it below the soil, you will also get a boost in microorganisms.

This provides the microorganisms that exist in the soil with food and in turn break down your compost into a usable product. 

3. Cover the compost

The easiest and most effective way to deal with unwanted algae in your compost bin is to keep it covered. 

When it rains, it will inevitably get washed into the compost, and algae loves moist, warm conditions. 

If you keep your compost covered, the algae will have a hard time growing and the beneficial bacteria in the compost will be able to work its magic. 

It’s important to keep the compost covered, though, for another reason. 

It’s best not to let too much sunlight get into your compost pile, as algae can also take advantage of that.

Sunlight is essential for photosynthesis, a process by which algae make food.

Covering also means limited supply of carbon dioxide.


In a perfect world, everything that comes out of your garden or compost pile would be perfect: loose, finely textured, and free of pests. 

Unfortunately, that’s not how it works out in reality. 

If you have a compost pile, you want healthy, dense, and disease-free compost, not a pile of sludge that smacks of dead fish. 

And we’re not just talking about the smell

Algae and fungi are a major problem in modern compost piles, and can potentially make the pile unusable.

With the information we’ve discussed on conditions under which algae thrives, you can feel confident that you can curb this problem, before you’re ready to mix the compost with your garden soil.

Zebedee Nambaleo
Zebedee Nambaleo

Zebedee is the founder of RealEstate Ke. He creates content by carefully examining and analyzing the real estate market, home improvement resources, and government data. His analysis is based on the principle of supplying high-quality, relevant, and in-depth information to his audience. By evaluating the current conditions and predicting future trends, he provides his audience with invaluable insights that allow them to make better decisions.