Join Shroomok on Shroomok Buy me a coffee or Shroomok Discord or Shroomok Reddit
Category: Contams & Troubleshooting

Shroomok's choice on Amazon

Why Mushrooms too Leggy, Fuzzy Feet and White Dots on Caps

Fuzzy feet and caps in mushroom growing
Fuzzy feet and caps in mushroom growing

What the long stems, fuzzy feet and fuzzy caps indicate

Okay, grower! You’re enjoying your own cultivation process, and suddenly notice your mushrooms are starting to grow a fuzzy stem, become leggy and strange fluffy white dots appear on the mushroom caps. Why this happen?

What is this fuzzy stuff? Is it contamination? What's wrong with such mushrooms? Is it possible to fix?

Lots of questions, so let’s get started!

First of all, it's not contamination! All these cases have the same main reason - lack of oxygen, lack of fresh air exchange (FAE) in fruiting chamber during fruiting period

Mushrooms too leggy

Mushrooms and mycelium breath like humans. They inhale oxygen (O2) and exhale carbon dioxide (CO2).

When oxygen level is too low, fruit bodies grow long stems to search for fresh air. As a result mushrooms have small caps and spindly stems.

Why mushrooms too leggy
Long stems and small caps due to lack of FAE

Fuzzy feet

In fact fuzzy feet is mushroom mycelium. It isn't huge problem. Moreover not contamination case!

Fluffy base of stems
Fluffy base of mushroom stems
fuzzy feet
Fuzzy feet
Fuzzy feet in mushroom cultivation
The base of mushroom stems are fuzzy. Photo by ChanandlerBong - Shroomok Growers Community on Discord

Such fuzziness is typically caused by two growing factors.

1. Lack of fresh air exchange (FAE) in fruiting chamber

As we know, CO2 is heavier than oxygen and concentration is higher at the bottom of the tube and lower as we go up. So that, the base of our shrooms will be the first area struggling to breathe.

2. High relative humidity level in combination with lack of FAE

So strange, isn't it? We know that mushrooms enjoy high humidity! It's true, however in this case high relative humidity influences gases ratio in fruiting chamber. When we increase humidity and add moisture, we are removing free space for oxygen in the air – thus, our mushrooms suffocate, and the fuzzy feet result.

Fuzzy feet aka fuzzy mushroom stem
Fuzzy base of stems. Photo by Leo - Shroomok Growers Community on Discord

Fuzziness or contamination?

Usually newbie growers confuse fuzziness symptom on stems and white dots on caps with Cobweb Mold contamination.

It's easy to identify fuzzy feet and cobweb disease. Just remember, cobweb has thiner threads and greyish color in comparison with snow-white mycelium

Fuzzy feet or contam
Snow-white Fuzzy Feet and white dots on caps is mycelium, not contam! Photo by ChanandlerBong - Shroomok Growers Community on Discord
Thin grey cobweb mold on mushroom cake
Thin grey Cobweb Mold contamination on mushroom cake

🔴 More examples: How to identify and get rid of Cobweb Mold

White dots or fluffy mushroom caps

One more example usually confused with mold contamination or mutation. But the reason is poor FAE again.

Fuzzy cap
Fuzzy cap. Photo by ʂƙı℘ɬཞı℘℘ıŋ - Shroomok Growers Community on Discord

Let me show you real case in Shroomok Growers Community on Reddit

Fuzzy mushroom caps and white dots on mushroom caps
Fuzzy mushroom caps. Case and photo by u/angelinejovan - Shroomok Growers Community on Reddit

angelinejovan: Contamination? Fuzzy caps! What the hell is this!?

shroomok: Looks ok so far, don't worry. It's just mycelium, not contam! Your shrooms need more fresh air, that's why fuzzy. Try to FAE 4-6 times/day

angelinejovan: Thank you for all your help! What a difference a day makes. Yesterday they were fuzzy, then after fanning every four hours religiously overnight the fuzzies have stopped growing. And I’ve been able to harvest over 7 ounces today. I am so ecstatic!! (BTW the fuzzies peel off the caps & stems)

How to fix fuzzy feet, fluffy caps and long stems?

Try to introduce more fresh air for your mushrooms. Usually in 2-3 days you can fix it easy.

Manual FAE. Open your fruiting chamber for 3-5 minutes at least 4-6 times/day.

Natural airflow in MonoTub. Properly made air vents in MonoTub create natural airflow. If air vents made wrong you have "dead zones" in the corners of your tub and poor overall FAE

🔴 Recommended: Monotub Guide

Use additional gadgets for FAE in fruiting chamber: aquarium air pump, PC fan or combination PC fan + humidifier

Shroomok's choice on Amazon:

Quiet PC Fan with power plug cord $19.99

Powerful Air Pump - for 20-200 Gallon - 2 Outlets - $19.99

Humidifier Fog Machine Mister 3L $49.77

Use CO2 detector to monitor air quality. CO2 level in fruiting chamber should be 600-800 ppm (up to 1000 ppm)

Shroomok's choice on Amazon:

Coreel Portable CO2 Monitor + Temperature & Humidity, LCD Display $46.99

INKBIRDPLUS Air Quality Monitor: CO2, Temperature, Relative Humidity for Grow Tents $69.99

7-in-1 Air Quality Monitor, Real Time Data Recording $129.99

Wrap it Up!

Mushrooms interact with us, always give us an exact sign what they need. Long stems, fuzzy feet and fluffy caps mean mushrooms are begging for a breath of fresh air.

Learn mushroom language, grower!

If you find this guide helpful you can 🍄 Buy Shroomok a mushroom as a donation and say something nice!

You can also request a Personal consultation on Growing Mushroom Troubleshooting

Be attentive to your shroom pets and have a happy growing!


Can you dry your shrooms with fluffy stems and consume it? Or do you need to scrape it off before you dry them?

Shroomok avatar Shroomok

@Joyshroom in fact fluffy stems is just mushroom mycelium. It's totally safe! No need to scrape it off


Thanks so much for this article, it's saved me from throwing away a potentially great grow as I was worried about it being contaminate.
I'll be introducing a lot more fresh air exchange now, and hopefully fix the issue.

Shroomok avatar Shroomok

@Ash, glad I could be of assistance. Have a happy growing!

You might be interested

Black spots on shrooms & mycelium

Strange black spots suddenly appeared on mushroom caps and mycelium. Why is this happening? Is it contamination or not?...

Read more

Sep 2022

Read more
Black spots on shrooms & mycelium

Bacterial blotch disease

The most prevalent bacterial disease affecting both commercially cultivated and home-grown mushrooms.

Read more

Oct 2023

Read more
Bacterial blotch disease

Natalensis: fruiting & overlay issues

All-in-one grow bag is not a magic pill, especially, when it comes to Natalensis cultivation. Aggressive behaviour of my...

Read more

Jul 2023

Read more
Natalensis: fruiting & overlay issues

Mycogone aka Wet Bubble

Shapeless masses, fluffy blobs of mycelium ooze with amber yellow orange brown liquid. Mycelium piss or wet bubble disea...

Read more

Feb 2023

Read more
Mycogone aka Wet Bubble

Green mold aka Trichoderma

Signs of Trich contamination. Why Trich appear on the 2-3 flush? Add one magic component and forget about Green Mold con...

Read more

Sep 2022

Read more
Green mold aka Trichoderma

Recent publications

Load more publications