Home » DIY: Natural Mold-Killing Laundry Detergent

DIY: Natural Mold-Killing Laundry Detergent

by Amanda Demsky
mold killer for clothes

Most homes are teeming in the thousands, if not millions, of various types of mold spores and any location that offers adequate moisture will provide it the perfect home. Laundry rooms especially provide the key ingredients to what makes mold grow: moisture, decaying organic material (soiled laundry), warmth, and usually no direct sunlight. Thus, it is not uncommon to find mold on clothes.


Mold On Clothes

The reason clothing is so susceptible to mold growth is not just because of the mold-inviting circumstances within the laundry room. Generally, when it is worn, clothing collects sweat and skin cells, as well as dirt and other forms of moisture and organic material that mold loves to feast on. Then, it is placed in the laundry hamper and usually sits for days before it it is finally washed. This scenario is typical and may not result in a noticeable mold infestation, but should the soiled laundry be allowed to fester long enough, a mildew smell may be present, as well as visible signs of green, blue, gray, black, or sometimes even white mold on clothes.

Another scenario is becoming more common due to busy lifestyles and poor habits. The quick development of mold on clothes after washing may be surprising to some, but it is quite an ordinary occurrence for those with overwhelmed schedules or those who are vulnerable to procrastination because they often forget to remove clothing from the washing machine once the cycle is finished. As time passes, this leads to the rapid proliferation of mildew and mold on clothes after washing, due to the remaining moisture. Neglecting to put the wet clothes in the dryer for a few hours is not what makes mold grow. Neglecting the clothes in the washer for 6 hours or longer–sometimes a day or even a few days–is the problem. Before too long, a mildew smell will be detected in the washer and clothing. Some assume this is the residue of soap, and while that may be true to some extent, the fact of the matter is that most soaps contains lard and other organic (even synthetic) materials that mold can thrive off of. The smell is not necessarily the residue of soap, but an indication that mold is producing a secondary metabolite–the mildew smell–from consuming that soap.

In rare cases, those suffering from diabetes (teamed with Candida yeast) or any illness caused by mold will display symptoms of mold sickness. One of those signs of mold sickness reveals itself in the victim’s clothing. Mold infection victims typically have high levels of sugar throughout their system. Therefore, one of their mold sickness symptoms is to release small levels of sugar through their pores and onto their clothing. This is the body’s desperate way of detoxing from sugar overload and ridding itself of what makes mold grow. If the clothing is not properly laundered right away, whatever types of mold spores are present in the home will find a most-welcoming habitat.

Whether the growth of mold on clothes is due to poor habits of leaving wet laundry in the moisture-trapping environment of the washing machine or it is due to the preexisting health problems caused by mold or mildew, a preventative and corrective strategy must be adopted. The first step is to end neglectful behavior in the laundry room. This could include routine mold prevention in the washing machine, such as MoldBlogger’s very own mold removal technique. The second step is to invest in a do-it-yourself mold killing laundry detergent recipe, such as the one below.

Mold Killing Laundry Detergent

Needed Items

Metal mixing spoon (or whisk)

Knife & safe cutting surface

Food processor (or cheese grater & glass bowl)

(50-60 oz.) Glass storage container with wide open mouth and secure lid

1 Tablespoon (preferably metal or glass) to leave permanently in the container


  • Two 5 oz. organic castile soap bars (naturally-scented with lavender or peppermint is great but non-scented works just the same)
  • 3 cups of washing soda (no, it’s not the same as baking soda)
  • 2 cups of borax
  • 30 drops of  certified-pure lavender essential oil (optional but highly advisable for a mold killing laundry detergent)

Other anti-fungal essential oils can be substituted for lavender, depending upon smell preference. Lemon, wild orange, tea tree or melaleuca, peppermint, or even white fir are all pleasant-smelling but potent ingredients for a mold killing laundry detergent.


  1. Cut the castile soap bars into small pieces or chunks. (This is crucial to avoid damaging the food processor.)
  2. Place the cut castile soap pieces or chunks in the food processor bowl. Pulse the soap on high until what remains are large crumbs.
  3. Add the washing soda to the food processor and pulse for 1 minute. (After pulsing, all the ingredients should be in powder form and well-combined. If not, try running the food processor again and then mixing with a spoon.)
  4. Empty the washing soda and castile soap into the storage container. Add the borax and blend well with a spoon.
  5. Add the essential oils of choice (optional but beneficial) and be sure to mix well.

Note: If no food processor is available, a cheese grater and a glass or porcelain bowl will suffice. Just be sure to mix the ingredients well with a spoon or even a whisk.


For traditional, top-loading washing machines: use 2 tablespoons.

For more modern, front-loading washing machines: use only 1 tablespoon.

Do not place the soap in the laundry soap drawers/dispensers. Instead, add this DIY natural mold killing laundry detergent directly in the wash basin with the clothes.

How Do These Ingredients Kill and Prevent Mold on Clothes?

Castile Soap: Castile soap is a plant-based concentration of olive oil, coconut oil, potassium hydroxide lye flakes, and distilled water. While it is a aggressive against fungi and very effective against dirt, grease, and other harmful microbials, it is gentle on sensitive skin types.

  • Olive oil: Olive oil is an effective mold killer because it contains an antioxidant known as hydroxytyrosol that damages the cell walls of various type of mold and yeast (specifically Candida albicans).
  • Coconut oil: Coconut oil contains lauric and caprylic acids that are extremely aggressive toward fungi and bacteria. In most studies, coconut oil completely obliterates mold growth, spores, and prevents regrowth.
  • Potassium hydroxide lye flakes: Potassium hydrozide lye flakes are best at preventing the growth of mold on clothes because it manipulates the pH of whatever substance or material it comes in contact with. Mold is very sensitive to changes in pH.
  • Distilled water: Distilled water may not kill mold but because the process of distillation results in a water that lacks microbial contaminants, it’s the best choice for any anti-fungal soap.

Making castile soap in bulk is easy and inexpensive, but to skip the extra work, a popular and affordable castile soap that is available at most stores is the Dr. Bronner’s brand.

Washing Soda: Washing soda, or sodium carbonate, is a highly-alkaline solvent. A solvent is able to dissolve other substances, such as mold. In fact, professional mold remediation services will use “soda blasting” as a means to dissolve and kill mold.

Washing soda is mainly available through the Arm & Hammer brand and should be easy to locate in most super stores. Do not confuse it with baking soda, which will render any mold killing laundry detergent recipe useless as a cleaning agent.

Borax: Borax, or sodium tetraborate, is a natural white mineral and salt powder compound derived from boron. It’s ability to make a substance or material into a mold-resistant and mold-killing environment makes it the most essential ingredient in any mold cleaner or mold killing laundry detergent.

Note: Borax is often mistaken for boric acid, which is extremely toxic and should not be added to household cleaners. Be informed and don’t miss out on such a cheap, effective, and versatile ingredient that is vital in most mold killing solutions just because some misread information and mistakenly believe that borax and boric acid are the same thing.


Essential Oils: While they are optional in this mold killing laundry detergent recipe, MoldBlogger highly recommends their use. Essential oils are plant-based and all plants contain various potency levels of anti-fungal, anti-microbial, antioxidal, and even insecticidal compounds as a means of self-defense and self-preservation against foreign invaders and rot and decay. They’re the perfect addition to any mold cleaner or mold killing laundry detergent and very effectual against all types of mold.


Whether clothes have been made susceptible to mold growth because of poor laundry habits or a preexisting mold infection within the body, there is always a natural and safe solution available. MoldBlogger’s DIY Natural Mold-Killing Laundry Detergent recipe is a quick, easy, and economical option that can prevent the growth of mold on clothes and assuage the health problems caused by mold and mildew.


Related Articles

DIY: Natural All-Purpose Mold-Killing Cleaner


About the Author: Amanda Demsky is the mother and personal chef of two boys, the domestic technician of a three-bedroom desert home, and occasionally, a freelance writer and editor. Feel free to follow her on Twitter @fullquiver777

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Hariah Rocha February 27, 2018 - 10:53 pm

Thank you very much for sharing this natural mold killing. Keep sharing on it.

Heidi April 7, 2018 - 4:38 pm

You said to use 2 Tblspn for top loading machines. What size load is that for. Doesn’t seem like enough.

Ann Elk August 24, 2018 - 1:23 pm

This is a great idea!
How much distilled water do you add? I can’t seem to find the description in the instructions.

Joan March 3, 2019 - 4:49 pm

This recipe works amazingly well! I moved into a house that wasn’t properly weather sealed during Maryland’s wettest summer on record. The air in my house was too humid and clothing stored in plastic bins and in lower drawers of dressers started to smell. Your Mold Killing Laundry Soap worked to remove the odor from most of the clothing. I use a tablespoon when washing towels and doggie smelling afghans, too. The Peppermint Castile Soap and lavender oil make such a great smelling combo! I do not have a food processor so I cut the soap bar in small chunks and turn them into fine crumbs in my old blender. Then I blend in the Borax in the blender, pour the mixture into a glass bowl and mix in the washing soda and lavender oil. Thank you for sharing this recipe!

ryann logan July 19, 2019 - 10:04 am

if using liquid castile soap, how much?

Sandra July 4, 2022 - 7:03 pm

Is this recipe effective for cold water washing? Typically cold water doesn’t dissolve borax. Is there a different suggestion for cold water wash?


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