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Growing mushrooms indoors is easier than you might think, and you can start harvesting fresh mushrooms right from a spare closet or countertop.
If you’ve been curious about how to grow mushroom indoors, the process boils down to creating the right humidity, temperature, and light conditions that mimic a forest floor.
You don’t need a green thumb or a backyard to make it happen, and today I’ll walk you through each step so you can grow mushroom indoors successfully.
By the end of this post, you’ll know how to grow mushroom indoors from spawn to harvest, what supplies to grab, and how to troubleshoot the common hiccups.
Let’s dig into the fun world of indoor mushroom growing.
How To Grow Mushroom Indoors: The Simple Setup
Growing mushrooms indoors all starts with understanding that mushrooms aren’t like plants that need soil and sunshine.
Instead, they thrive on a substrate like straw, sawdust, or coffee grounds, and they love dark, damp, and cool spots.
If you’re ready to grow mushroom indoors, the first decision is choosing which variety you want, since some are more forgiving than others for beginners.
Oyster mushrooms are often the best choice when you’re learning how to grow mushroom indoors because they grow fast and tolerate a wider range of conditions.
Shiitake and lion’s mane are also great options, while button mushrooms require a bit more patience and precision.
Once you pick your variety, you’ll need to gather a few key supplies to get started on your journey to grow mushroom indoors.
1. Choose Your Mushroom Kit or Spawn
The easiest way to grow mushroom indoors for a newbie is to buy a pre-made mushroom grow kit.
These kits come with a fully colonized substrate block and just need you to follow the simple instructions for fresh air and misting.
If you want more control, you can buy spawn (which is like mushroom “seeds” mixed with grain) and mix it into your own substrate.
Either way, starting with quality spawn is the foundation to successfully grow mushroom indoors.
You’ll also want a spray bottle for misting, a plastic tub or bag, and a thermometer to monitor the environment.
2. Prepare Your Growing Container
When you grow mushroom indoors, your container can be as simple as a plastic tote with a lid, a large jar, or even a bucket with holes drilled in the sides.
The key is creating a humid microclimate inside the container so the mushrooms don’t dry out.
Poke a few small holes in the container to allow for fresh air exchange, because mushrooms release carbon dioxide and need oxygen to fruit properly.
You can line the bottom with perlite or moist paper towels to boost humidity, which is crucial when you grow mushroom indoors in a dry house.
3. Prepare the Substrate
The substrate is the food source for your mushrooms, so this step is vital if you want to grow mushroom indoors successfully.
For oyster mushrooms, pasteurized straw works wonderfully, while shiitake prefers hardwood sawdust or supplemented wood chips.
You’ll need to pasteurize the substrate by soaking it in hot water (around 160-170°F) for an hour, which kills off competing molds.
Drain the substrate, let it cool, and then mix in your spawn at a ratio of about 1 part spawn to 5 parts substrate.
This mixture then goes into your prepared container, and now the real waiting game begins when you grow mushroom indoors.
Best Conditions To Grow Mushroom Indoors
Now that your container is set up, you need to dial in the perfect environment to grow mushroom indoors.
Mushrooms are picky about temperature, humidity, and light, so let’s break down each factor so your mushrooms don’t stall out.
Get this right, and you’ll be amazed at how quickly those little pins appear when you grow mushroom indoors.
1. Temperature Control
Most common indoor mushroom varieties prefer temperatures between 55°F and 75°F, depending on the species.
Oyster mushrooms like the cooler end of that range, around 60-65°F, while lion’s mane prefers slightly warmer, around 65-70°F.
You can easily grow mushroom indoors at room temperature, but avoid placing your container near heating vents, radiators, or in direct sunlight.
If your house is too warm, mushrooms may grow leggy, and if it’s too cold, they’ll stall out completely.
2. Humidity and Misting
Humidity is the most critical factor when you grow mushroom indoors, because mushrooms are about 90% water.
You need to keep the air around your substrate consistently moist, ideally at 80-90% relative humidity.
Mist the inside of your container and the substrate surface twice a day with a fine spray bottle, but don’t soak the substrate directly.
If you live in a dry climate, a small humidifier in the room can work wonders to help you grow mushroom indoors.
3. Light Requirements
Contrary to popular belief, mushrooms don’t need sunlight to grow, but they do need indirect light to trigger fruiting.
A north-facing windowsill or a few hours of ambient room light is plenty when you grow mushroom indoors.
Some growers use a low-wattage LED light on a 12-hour cycle, which mimics the dappled light of a forest canopy.
Just never place your mushrooms in direct sun, as it will dry out the substrate and scorch the delicate caps.
From Spawn To Harvest: The Mushroom Growth Phases
Once your environment is set, you’ll watch your mushrooms go through two distinct phases as you grow mushroom indoors.
The first phase is called colonization, where the mycelium (the root-like network) spreads through the substrate.
During colonization, which takes about 1-3 weeks, you won’t see any mushrooms yet, just white, fuzzy growth on the substrate.
Keep the substrate in a dark spot and don’t open the container too often during this stage.
1. Triggering Fruiting
Once the substrate is fully colonized (it’ll look completely white), you need to trigger fruiting to grow mushroom indoors.
This is done by introducing fresh air and lowering the temperature by about 5-10 degrees, which mimics the change from fall to winter.
You’ll also expose the container to indirect light at this point, and you might even add a layer of moist casing soil for some species.
Within a week or two, you’ll see tiny white pins forming on the surface, which are baby mushrooms.
2. Watching Them Grow
Those pins will double in size every day, so keep misting and providing fresh air as you grow mushroom indoors.
Oyster mushrooms can go from pin to harvest in just 4-7 days, which is incredibly rewarding for a beginner.
Check on your mushrooms twice a day, because they can grow so fast that they might surprise you overnight.
3. Harvesting Your Mushrooms
You’ll know it’s time to harvest when the caps flatten out and the edges start to curl upward slightly.
Twist the mushroom at the base and pull it gently from the substrate, or use a sharp knife to cut it cleanly.
Don’t pull out the entire root network, as the substrate can often produce a second or third flush of mushrooms.
After the first harvest, keep misting, and you might see a new batch of pins within a couple of weeks.
Troubleshooting When You Grow Mushroom Indoors
Even with the best care, you might run into a few issues when you grow mushroom indoors, but most are easy to fix.
If your mushrooms look dry and cracked, you need more humidity, so mist more often or add a humidifier.
If you see green or black mold on the substrate, that’s a sign of contamination, and you’ll need to remove that spot immediately.
Long, skinny stems with tiny caps usually mean insufficient fresh air, so open your container vents more frequently.
1. Common Pests
Fungus gnats and fruit flies are the most common pests when you grow mushroom indoors.
These little bugs are attracted to the moist substrate, but they’re more of a nuisance than a real threat to your mushrooms.
You can place sticky traps near your container or cover the substrate with a fine mesh to keep them out.
2. Slow Growth
If your mushrooms just aren’t growing, check your temperature first, as a drop too far can stall everything.
Also, make sure your substrate isn’t too wet or too dry, as both extremes prevent fruiting.
Patience is key when you grow mushroom indoors, but if you go three weeks without any pins, try lowering the temperature slightly.
So, How To Grow Mushroom Indoors Successfully?
You can grow mushroom indoors successfully with just a few supplies and a bit of patience.
Mushrooms grow indoors as long as you provide the right substrate, humidity, and temperature.
We covered everything from choosing spawn and pasteurizing substrate, to dialing in the environment and harvesting your first crop.
Whether you’re using a simple kit or building your own setup, the joy of harvesting fresh mushrooms from your own home is unbeatable.
So grab some oyster mushroom spawn, set up a container, and start your indoor mushroom growing adventure today.
The reward is a fresh, delicious harvest that’s well worth the effort.