How to Grow Mushrooms Indoors! | Almanac.com

How to Grow Mushrooms Indoors!


Growing mushrooms at home in two weeks

The Editors

Growing mushrooms indoors is a lot of fun because these immune system-boosting treats grow very fast (as quickly as two weeks).  Are you a fungi fanatic? Join us as we explain how to get started growing mushrooms—and take your ‘shrooms all the way through harvest!

You can practically watch mushrooms grow before your very eyes. In only two weeks or so, you can be picking your own immune system-boosting gourmet treats with these easy-to-grow methods.

Warning: As we wrote this, we couldn’t help but roll out the mushroom puns! We’re just a bunch of fun guys (“fungi”—get it?). Mushrooms are great in any meal—even breakfast with eggs; in fact, they’re the breakfast of champignons. They’re all delicious, that’s the morel of the story! (Sorry, if these puns were in spore taste!)

Start with a Mushroom Kit

OK, let’s get back to business. It really helps to watch the video for this project. We’re going to start off some mushroom kits: one for growing oyster mushrooms (which uses a two-gallon pot stuffed with straw) and another ready-to-go kit that uses coffee grounds as its growing medium.

Note: Do not eat just any mushroom which may not be edible. Only buy your mushroom spores and kits from reputable sources. A couple U.S. supplies are:

North Spore
Fungi Ally

Oyster Mushroom Kit

The kit uses a large pot of around 2.5 gallons, or you could use two pots of half this volume each. The growing medium is straw, pressed into pellets and ready to be rehydrated.

  • Prepare the pot: Clean the pot then sterilize with a dilute household bleach solution. Cover the drainage holes with a circle of cut-to-size cardboard, pushed to the bottom of the pot. Cut in holes into the sides—three holes of around a half inch in diameter, using scissors. Space them evenly around the circumference and also evenly from bottom to top.
  • Prepare the strawn and grain: Break up the grain, which has the spawn of the mushrooms in it. Empty the straw pellets into the pot then add the broken-up grain kernels to the straw pellets and mix well to evenly distribute. Make sure to use very clean hands for this so you don’t introduce any unwanted germs! Best to do this outside to make a mess.
  • Water: Measure out about a gallon of water and then very slowly trickle-pour half of this over the spawn mix. Allow the water to become fully absorbed—around half an hour—then add the rest of the water, slowly. Once the straw pellets have fully rehydrated to fill the pot, push back the straw from your three holes to leave a cavity. This will keep this area moist and protected, so the mushrooms can properly develop.
  • Make the lid: The lid will stop everything from drying out. A simple way to make one is to cut out a round of stiff cardboard to fit then wrap this in clear food wrap or plastic wrap.

Now it’s prepared we just need to offer warm conditions for the mycelium—or mushroom ‘roots’—to grow. Room temperature is ideal but keep the pot away from direct sources of heat. If it’s the summer, you could keep the pot outdoors, somewhere sheltered and out of direct sunlight.

To keep things going, simply mist-spray the holes a couple of times a day. This will stop the straw from getting too dry, offering that moist environment that mushrooms need.

And here it is after two weeks, with the straw now totally white with mycelium. At this stage our kit’s ready to produce its first flush of mushrooms!

Continue to mist the holes twice daily and within a week or two you should notice small clusters of primordia—the beginnings of the fruiting bodies—the mushrooms—that we’ll be picking. At this stage misting becomes even more important as you really don’t want these to dry out. They’ll soon swell into full-sized mushrooms, and this shouldn’t take more than about a week after spotting the primordia.

The best time to harvest oyster mushrooms is before the caps have fully flattened out, when they will dump lots of spores everywhere! Twist free the whole cluster at once—the mushrooms will be different sizes and that’s fine—and trim any stump out with a sharp knife, right back to fresh straw. Continue misting, and you can expect new mushrooms to sprout from the harvested hole in due course. They should keep cropping every few weeks for up to around 10 weeks.

Coffee Grounds Kit

I hate waste, and your daily cup of Joe creates quite a bit of it in the form of these: coffee grounds. But what if you could turn them into these! That’s what this kit does, which uses coffee grounds, mixed with a little straw to create the ideal growing medium for our mushrooms. Let’s get it started.

Cut open the front of box and cut out a cross into front of the bag. Then soak the bag overnight, let it drain off then pop back into the box. Mist the front of the box that’s cut open with water twice a day. Keep the kit on a windowsill or work surface out of direct sunlight and, again, avoiding direct sources of heat. 

And here you can see the primordia—about seven days after opening your kit and starting it off. These grow very quickly—doubling in size almost every day! Again, harvest the mushrooms when the caps have just started to open out but haven’t  yet flattened out. Flattened out mushrooms don’t store for quite as long and aren’t quite as firm and flavorsome. To harvest, simply twist and pull them away with your hands like this.

You can grow a follow-on flush of mushrooms, too. To do this, allow the kit to rest for two days following harvest then just soak the block in water just as you did when you started it off. Weigh it down if necessary. Lift it out, allow the excess moisture to drain off then pop it back into the box and mist regularly, as before. The second crop should follow on within a couple of weeks or so. And once you’ve had that harvest, repeat the process once more!

Cooking with Mushrooms

Mushrooms are so versatile, great with eggs or in a pasta dish or in an Asian soup. If you’re vegetarian, mushrooms help achieve a warm, savory meal without meat. A simple recipe for your first harvest is seared mushrooms. 

Seared Mushrooms with Garlic
Heat a couple of tablespoons of olive oil in a large skillet over medium-high until just beginning to smoke. Cut up mushrooms in large pieces and arrange in skillet in a single layer and cook, undisturbed, until bottom side is golden brown, about 3 minutes. Season with salt and pepper, toss mushrooms, and continue to cook, tossing often and reducing heat as needed to avoid scorching, until golden brown all over, about 5 minutes more. Optional: Reduce heat to medium and add a couple tablespoons of butter and a couple of crushed garlic cloves if you wish. If you have fresh thyme, add chopped thyme leaves.

Here are a few more recipes to try with mushrooms:

Mushroom-Spinach Quiche

Noodles and Mushrooms

Stuffed Mushrooms

Mushrooms are pricey. At least, decent mushrooms like these are. But by growing your own you can be sure of perfect shrooms at peak freshness—and for a lot less than the grocery store. They’re so powerfully good for you too: great for the immune system and for fighting off diseases. Have you grown mushrooms before, and what’s your favorite variety? We’d love to hear from you. 


Mary Ann Smith (not verified)

5 months ago

Another kit company that is widely available and offers discounts regularly with their website is Back to the Roots. We have used their kits several times and had good results. If you take a picture and post it, they also donate a box to a school. It used to be a school of your choice, but COVID lead them to focus efforts on schools in underserved communities. We have also bought them in local stores. Sometimes apps like Ibotta and FetchRewards have also had cash back for purchases of these. Good luck with your mushroom growing.