When Do I Introduce Light, Oxygen, and Humidity for my Mushrooms?
Posted by Marz on Oct 22nd 2025
Getting to the bottom of Light, Oxygen, and Humidity for Growing Mushroooms
When Do I Introduce Light, Oxygen, and Humidity to my Mushrooms? This is a super common question asked amongst many beginners and long-time growers who just haven’t grown in a while. Either way, no shame here at Spore Genetics! We’ve got your back. Below I will provide the best time to start your light, fresh air exchange, and humidity for your mushrooms. This information will hold true across all mushrooms, unless stated otherwise for a particular mushroom.
The best time to start introducing light, fresh air exchange, and humidity will be whenever your cakes are 90-100% colonized. The reason I say 90% or above is simply because nature is nature and sometimes the mycelium isn’t always going to full blown colonize everywhere. You might be waiting for that extra little bit to colonize out and now your cakes are getting too stressed because it’s ready to move to the next phase of its life cycle.
How Long Do I Keep Mushrooms in Light?
You should aim anywhere between 8-12 hours of light per day. You do not need sunlight for mushroom growing, but you can absolutely use natural light if you choose. There are definitely some mushrooms that enjoy sunlight more, but this should be specified on the mushroom you’re growing so don’t stress. An LED light hanging above your cakes will suffice. Light is just strictly for directional growth when it comes to indoor mushroom growing.
How Much Humidity Do I Need For Mushrooms?
Typically, 80% and above will be a great range for your mushrooms. Of course, there are some that need to be around 100% consistently such as Panaeolus Cyanescens. Purchasing a hygrometer can greatly help keep an eye on how much humidity is in your mushroom cakes’ environment.
Fresh Air Exchange (FAE) For Mushrooms
There are many ways you can incorporate fresh air for mushrooms. If you have a monotub/tote you can always take the lid off a few times daily for a few minutes each time. A key pointer I will mention is to make sure all fans/ac units/vents are off and closed off so there is no moving air around you.
If you have a Laminar Flowhood, this is the best possible way to give your mushrooms fresh air exchange. Just simply start your flowhood about 15 minutes before actually starting and then take your lid off and allow the clean air to waft out any CO2 for a few minutes. Try to aim for 2-3 times per day.
If you are growing in a mushroom tent, having a fan that pulls outside air in will work perfectly. A good rule of thumb is to make sure you have some type of filter that filters the outside air in. You don’t need to keep it running at a constant, this will tend to dry out cakes. Either manually turn on for about 10-15 minutes as this needs more time to air out an entire tent. You may also connect it to a timer for 15 minutes every 4 hours.
Adjust any of these suggested times as you observe your cakes. Some may need more air, less air, more humidity, less humidity, and so on & so forth. You also may need to adjust simply based on your living environment.
Purchasing a thermometer and hygrometer can greatly benefit you keeping track of your environment. If you have further questions, always feel free to contact us!