Can Grow Bags Be Used as Compost?


Grow bags are a lightweight, breathable alternative to pots. They can prevent plants from running out of room for their roots, which can happen in pots. There are plenty of benefits to using a grow bag instead of a pot for your plant, but many people wonder whether or not they are compostable. 

Grow bags can be used as compost if they are made from natural fabrics like hemp and natural felt. Grow bags made from polypropylene—which is a type of plastic0—are not compostable. Always check what material your grow bag is made from before attempting to compost it. 

The rest of this article will go into more detail about composting wgrow bags, including which ones are compostable, which ones aren’t, and more. Let’s get started!

Can You Compost Your Grow Bags?

Not all grow bags are compostable, as most of them consist of materials that are not biodegradable. Remember, for something to be used as compost, it needs to be biodegradable. 

Most manufacturers use polypropylene to make grow bags. Polypropylene is a flexible type of plastic commonly used for making straws and plastic bottles. Many consider it safer than other types of plastic because it does not contain the chemical compound BPA (bisphenol A). Experts have linked BPA to several health problems making it less than ideal for humans and plants. 

But just because it does not contain BPA doesn’t mean that polypropylene is safe to compost. Polypropylene is still a type of plastic that will not biodegrade. 

For something to biodegrade, it must break down completely. 

A biodegradable substance is something that can be broken down naturally by bacteria, a process that leads to decomposition. Plastic is not biodegradable, meaning that it will not decompose. Over time, it doesn’t break down: instead, it disintegrates.

Plastic Breaks Up Into Smaller Pieces

Under the right conditions, plastic can disintegrate into smaller pieces. This process of disintegration continues until, at some point, the pieces become too small to see with the naked eye. This happens in landfills often.

Plastic can take millennia to completely break up into these little fragments. So, trying to compost plastic will simply leave you with smaller pieces of plastic that have persisted. 

Because plastic will not break down completely, we can’t compost grow bags made of polypropylene. If you try to do so, you will be stuck with smaller pieces of plastic in your compost pile which can slow down the entire composting process. Having non-biodegradable materials in your compost is extremely bad for it, as we will discuss later in this article. 

In order to use your grow bags as compost, you need to invest in grow bags made from compostable materials.

Alternatives to Polypropylene Grow Bags

Hemp Fabric Grow Bags

If you are looking for a compostable grow bag, you can look into grow bags made with hemp fabric. These are a great alternative to polypropylene as they are biodegradable and compostable. 

Hemp fabric comes from the cannabis sativa plant. If you separate the outer layer of the stem of this plant, you can spin the layers together to create yarn. Manufacturers use this yarn to create grow bags from a more natural source. Because of the intricate process involved, these grow bags made with hemp fabric can be more expensive than polypropylene. 

Because hemp fabric comes from natural materials, you can add it to your compost pile without fear. It will biodegrade, unlike polypropylene, in weeks or months, depending on the condition of the pile. It is also good for your compost as it is rich in carbon and will provide a good energy source for microorganisms as they work to biodegrade the materials. 

Felt Grow Bags

Felt is also a popular material for fabric grow bags. Its ability to promote the circulation of air in the soil makes it ideal for plant growth. As long as your felt grow bag is made from natural fibers and isn’t blended with synthetic materials, it will be safe to compost. 

One drawback of felt grow bags, however, is their high porosity, meaning that water passes through them relatively quickly. As a result, you may need to water your plants more often. 

If you do go the felt route, check your soil’s moisture levels regularly and adjust your watering schedule accordingly. You can also consider mulching as a way to prevent excessive water loss.

What To Do With Grow Bags That You Can’t Compost

If you are unable to compost your grow bags, it doesn’t mean they need to go to waste. The best thing you can do with your grow bags is to reuse them whenever possible.

This is why it is so important to take good care of your grow bags when using them. Things like cutting or poking holes in the grow bags can affect whether or not you can reuse them. Otherwise, grow bags typically have a shelf life of about five years and can be safely reused as long as you clean them between uses: Should You Put Holes in the Bottom of a Grow Bag

If you have no use for your grow bags over the winter months, that’s okay. They can remain empty until it’s time to start using them again. Before you put them away for the winter or just until you have another plant for them, make sure you wash them thoroughly.

Cleaning fabric grow bags can be different from plastic ones due to their materials. Check out my guide to learn the best way for cleaning and preserving your fabric grow bags: How to Clean Fabric Grow Bags (Complete Guide)

Once the grow bag is clean, ensure it is completely dry before you put it away to prevent mold from taking over it during the winter. 

If the bag is no longer usable, then you will need to do away with it. Dropping your used grow bags off at a nearby recycling center is a great way to responsibly dispose of them.

The Risk of Composting Plastic

If you have grow bags made from polypropylene, you shouldn’t compost them. While all the material inside a grow bag will compost just fine, the bag itself will not. Not only will it refuse to break down, but it can also ruin your compost pile. 

You should avoid putting plastic in your compost pile at all costs, grow bags included. This is because plastic sheds fragments during the composting process that are not biodegradable. While microorganisms can degrade some forms of plastic, there is a limit to how much they can break down and how much time it will take them.

Because of this, over time, all you will be left with is chunks of plastic in your compost pile. 

These plastic chunks may seem like nothing more than little bits you can pick out and toss to the side, but they can actually greatly impact your compost pile. If you have materials in your pile that do not break down like others, they will affect the pace of degradation for the remainder of the pile.

Plastic Is Bad for Your Compost Pile

Large chunks of plastic in your compost can lower the overall temperature of your pile. This will make it more difficult to get a uniform temperature going throughout, which is vital for the composting process to complete. Plastic can also hinder the microorganisms from reaching other materials that need biodegrading, causing further delay. 

Overall, you should not add plastic to your compost pile if you want the pile to remain uniform and usable. Otherwise, you will have parts of the pile that do not completely degrade while others finish. Plastic, like other non-biodegradable materials, is a hindrance to composting and mostly gets in the way of the process.

Final Thoughts

Grow bags are a convenient way to hold plants without needing a heavy pot. Unfortunately, you cannot compost them unless they are fully made of natural materials, and most of them aren’t. 

If your grow bag isn’t compostable, it doesn’t mean you need to throw it away after you use it or your plant grows out of it. We recommend reusing your grow bags as much as possible. Once they’re no longer usable and you’ve disposed of them, you may switch to a compostable grow bag, like those made with hemp fabric or natural felt.

Alexander Picot

Alexander Picot is the principal creator of TheGrowingLeaf.com, a website dedicated to gardening tips. Inspired by his mother’s love of gardening, Alex has a passion for taking care of plants and turning backyards into feel-good places and loves to share his experience with the rest of the world.

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