Mold growth is a common concern for backyard mushroom growers. If fuzzy mold starts growing in your Back to the Roots mushroom kit, don’t panic! With a few simple steps, you can get rid of the mold and get your mushrooms growing again.
What Causes Mold in Mushroom Kits?
There are a few main reasons mold can start growing in your mushroom kit
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Too much moisture – Mushrooms need moist conditions to grow, but too much water can lead to mold. Make sure you’re not over-watering.
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Insufficient air circulation – Stagnant air and poor ventilation gives mold spores a chance to take hold. Make sure your kit has airflow
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Spore contamination – Tap water and dust can introduce mold spores to your kit. Use distilled or boiled water when moistening.
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Too warm – Mold thrives in warmer temps above 70°F. Keep your mushroom kit around 65-68°F.
Identifying Mold in Your Mushroom Kit
Mold can start growing on the surface of your mushroom substrate, appearing as fuzzy splotches of white, gray, green, black or blue. It may cover small patches or take over the entire surface.
Some common molds found in mushroom kits include:
- Penicillium – Blueish gray or green mold with a velvety texture
- Aspergillus – Fast growing black mold with a powdery appearance
- Trichoderma – Fluffy white or green mold that can spread rapidly
- Mucor – Thick, black pin-cushion like mold
If you notice any fuzzy growths that aren’t pure white mycelium, it’s likely mold.
Fortunately, catching it early makes it easier to get rid of.
Removing Mold from Your Mushroom Kit
If mold is growing in your mushroom kit, here are some tips to get rid of it:
1. Isolate the Kit
The first step is to isolate the contaminated mushroom kit. Move it away from other grow kits to prevent mold spores from spreading. Work in a well-ventilated area and cover surfaces with paper towels.
2. Scrape Off Visible Mold
Use a sterilized fork or skewer to gently scrape off any visible mold. Try to remove it entirely from the surface of the substrate. Discard the debris in a sealed bag.
3. Increase Air Flow
Improve airflow by propping up the lid of your grow kit, fanning it periodically, or placing it near a fan. Circulating air will dry out the surface and prevent future mold growth.
4. Decrease Moisture
Cut back on misting and watering to allow excess moisture to evaporate. For 1-2 days, stop watering completely. Then resume a lighter watering schedule, so the substrate stays evenly moist but not soaked.
5. Apply Hydrogen Peroxide
Using a spray bottle, lightly mist the affected areas with 3% hydrogen peroxide. This will kill off mold spores. Let it bubble for a few minutes before rinsing with clean water.
6. Apply Salt or Baking Soda
Sprinkling salt or baking soda on the substrate creates an inhospitable environment for mold. Let it sit for an hour before rinsing it off.
7. Lower Temperature
Heat encourages mold growth. Try relocating your mushroom kit to a cooler spot around 60-65°F.
Preventing Future Mold Growth
Once you’ve dealt with the active mold, make a few adjustments to prevent it from recurring:
- Use distilled or boiled water since tap water can contain mold spores.
- Sterilize any equipment that touches the substrate by dipping in rubbing alcohol.
- Check that your kit has adequate ventilation.
- Maintain a consistent moisture level – moist but not soaked.
- Keep temperatures cool, around 65°F.
- Avoid disturbing or handling the substrate once mushrooms start fruiting.
- Isolate any contaminated kits quickly to keep mold contained.
Stay vigilant for small patches of mold and address them early before they spread. With good growing conditions and proper care, your mushroom kit will be mold-free and ready for a bountiful harvest.
When to Toss Your Mushroom Kit
If the mold persists after several removal attempts, it may be time to discard the kit. Heavily contaminated kits that are covered in mold won’t produce quality mushrooms.
Signs that your mushroom kit is too far gone include:
- Mold covers more than a quarter of the substrate surface.
- Mushrooms are stunted and weak or turning colors.
- Mold returns within days of removing it.
- You detect a foul, musty odor from the kit.
Sterilize and safely dispose of kits that are too moldy to salvage. Then start fresh with a new mushroom grow kit. With better moisture control and ventilation, your next attempt will be mold-free.
Frequently Asked Questions About Moldy Mushroom Kits
Is mold dangerous to eat?
It’s not recommend to eat mushrooms that have grown in contaminated kits. Certain molds can produce toxins that cause health issues. Always discard moldy mushrooms to be safe.
Can I still harvest mushrooms?
If the mold is isolated to small patches and your mushrooms seem healthy, they are likely still OK to consume. Carefully cut mushrooms at the base rather than pulling and wash thoroughly.
Will spraying bleach kill the mold?
Bleach is not recommended for mushroom kits. The chlorine can negatively interact with the mycelium and bleach doesn’t penetrate porous materials well. Use hydrogen peroxide instead.
How do I sterilize my grow kit after mold?
Scrub off debris with soap and water, then soak the kit in a 10% bleach solution for an hour. Rinse thoroughly. Microwaving substrate will also kill mold but may impact future growth.
Why is the mold growing back quickly?
Rapid regrowth means there are residual mold spores embedded in the material. Remove 1/2 inch of substrate around the affected area to fully eliminate. Increase air flow and decrease moisture.
Taking a few simple precautions will help prevent mold from becoming an issue in your Back to the Roots mushroom kit. Monitor moisture levels, air flow, and temperature regularly. Address any mold promptly before it spreads. With quick action, your mushroom harvest will be safe from mold and ready for the dinner table.
What to do if you see an outbreak
In the unlikely event you get an outbreak, here are some tips:
- Put some tape over any holes directly over the outbreak. This will keep its spores inside the bag and keep it from getting oxygen.
- Draw a rough outline of the outbreak with a marker pen. This will more easily indicate if it’s growing or receding.
- Move it to a different location. This one might be too hot or too cold, which helps mold grow instead of mushrooms.
- Taking the kit outside and putting the mold in direct sunlight (UV) will help. The mushroom mycelium should tolerate this without too much damage.
Are the mushrooms still edible?
Even if mold is inside the bag and the mushrooms are still growing, it usually won’t affect the fruit bodies, so the mushrooms should still be fine. There is no way for the mold to get into the mushrooms like it could a loaf of bread. However, cobweb mould grows on the surface, and can cover the fruit bodies with a fluffy white coating. This causes the mushrooms to rot quickly. If you suspect cobweb mold, discard the grow kit if you see this.