It’s one of the best gardening tools.

Grow bags are an excellent alternative to using containers for growing plants. But they do have their pros and cons.

Grow bags get moldy due to excess moisture and lack of sunlight in humid and wet conditions. You can use baking soda, vinegar, or hydrogen peroxide to remove the mold. Prevent mold by keeping the grow bags in a dry location.

In this post, I’ll help you get rid of any mold from your grow bags. I’ll also give you tips on preventing mold from reaching the grow bags in the first place.

Why does mold grow on grow bags?

Mold grows on grow bags because the bag has been in a dark and damp place. If you overwater your plants in grow bags, the soil and bag remain damp and provide a growing environment to the mold and new mold spores.

When you keep your grow bags in a relatively shaded environment, or when there are a lot of them next to each other, that provides the darkness that mold loves. In addition to darkness and moisture, mold thrives when the air is still and not well ventilated.

How do I know if my grow bag has mold?

Your grow bag has mold if you see signs of discoloration, sliminess, and an unpleasant odor. Make sure to check the grow bag every day as part of your gardening routine.

Grow bags are predicted to last 7 to 8 seasons, but with good care, they can last for much longer. (

How to remove mold from grow bags?

You can remove mold from grow bags using a solution made using baking soda, vinegar, and water. You can also remove the mold using a solution of hydrogen peroxide and water.

If you have a mold problem on your grow bags, you should not worry too much. Mold, fungus, and moss are easy to remove, and very few molds are going to be harmful to your plants. Moss can be helpful to your plants by keeping the soil moist and full of nutrients, and fungus can help break down debris and provide nutrients for your plants.

While the mold or other growth in question has likely permeated the grow bag’s fabric, you do not have to remove the plant and its soil to remove the mold. You can create a solution in a bucket or bowl of baking soda, vinegar, and water.

Using a soft-bristled scrub brush, dip it in the mixture and scrub the affected areas of the bag until all of the mold, moss, or fungus has been removed. You should then let the container air dry in a dry place and ideally in the sun.

Another method for removing mold from a grow bag requires hydrogen peroxide. Dilute some hydrogen peroxide in a spray bottle and spray the moldy areas of the bag. Make sure not to put enough that it will damage the roots, and once the mold is gone, rinse the outside of the bag.

spray bottle
Spray bottle I use to water or spray neem oil

Once the gardening season is over, you should thoroughly clean your grow bags inside and outside with the same solution and technique as the first removal tactic. Allow the bags to fully air dry, preferably in the sun, before folding them up and storing them until next season.

The biggest reason that grow bags get moldy is when they never get the chance to dry. Constant wetness is a breeding ground for bacteria. The best way to remove mold is to soak them in a hydrogen peroxide solution and then leave them out to dry completely. To create the solution, combine 1 quart of lukewarm water with ¼ cup of hydrogen peroxide, and let the bags soak for 30 minutes. – Jeremy Yamaguchi, CEO, Lawn Love

How to prevent mold from growing on grow bags?

You can prevent mold from growing on grow bags by avoiding overwatering plants. Keep the grow bags in a sunny location and have sufficient distance between them. This avoids a moist environment that can encourage mold from growing.

The best way to prevent mold from growing is to target the conditions that allow mold to grow in the first place.

When it comes to moisture, take precautions not to overwater your plants. Water the soil only when it is dry, and never let water pool up above the soil.

Put your grow bags in a sunny spot and space them out a bit. This way, mold will not have a dark place to begin growing. If mold persists or you do not have a fully sunny place, rotate the bags periodically so that every side gets some time in the sun.

Finally, create plenty of ventilation, so mold particles in the air have nowhere to settle. You can provide your plants with a small fan to keep the air moving, or you can make sure they are in a place where they will get a frequent breeze.

Does growing indoors make grow bags more susceptible to mold?

Growing indoors makes grow bags more susceptible to mold because the environment can get dark and humid. Those are conditions mold spores prefer to latch on to the grow bags.

Mold spores are everywhere, but most people think about mold only when their house starts smelling like mildew. The truth is that mold grows anywhere there is dampness and warmth.

It thrives in bathrooms, basements, garages, sheds, and closets that are dark, warm, and humid.

Moisture is great for plants and all life, including mold. Too much humidity and moisture will encourage mold growth on your bag. Keep water from spilling over the exterior and uncovered surfaces of the bag and wipe it off where possible. Keep the bag in the sun for much of the day. This will help kill growing mold, which likes the dark. Also, be on the lookout for leaves, dirt, or other debris on the bag as these provide cover for mold to crop up. – Chelsea, Love From Our Backyard

How do you clean a grow bag?

Grow bags are made from plastic or fabric and are easy to clean. Simply wash them with soap and water. Not washing your grow bag often enough could lead to mold growth.

If you want to remove any dirt or debris, use a brush or sponge. Do not scrub too hard though; this may cause holes in the material.

After cleaning, leave the grow bag outdoors overnight to dry completely. Once dried, fold the bag back into shape and store it away until next year. 

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