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How To Grow Portobello Mushrooms At Home: Our Complete Guide

Growing portabellas indoors is easy. Fill a 4 x 4 foot tray with five-to-six inches of compost, add your portabella spores, stir them in, and wait for two weeks. When you see a fuzzy white film, cover it with moist peat moss and newspaper. Your portabella mushrooms will be ready soon!

Love Mushrooms? Grow Your Own!

I highly recommend learning how to grow portobello mushrooms because it’s fun, it saves money, and mushrooms are so much tastier when they’re fresh. 

I’m particularly fond of portabellas because of their wide caps, which look elegant on a plate and also make a diet-friendly alternative to hamburger patties.

Want to grow delicious, healthy portabella mushrooms like these at home? Read my tutorial to learn how!

How To Grow Portobello Mushrooms Indoors Or Outdoors

If you ask me, mushrooms deserve more love than they get. They tend to be treated as a culinary accessory — you can get them on your pizza, or not. Order mushrooms without the pizza, I say! 

They have an earthy flavor like nothing else and some of them even taste meaty. I use them to make gravy, veggie burgers, and soups.

The mushroom growing process can fascinate adults and kids, alike. Additionally, mushrooms are an ideal indoor crop because they need little light. Apartment dwellers, rejoice!

There are all sorts of ways to grow mushrooms from the comfort of your home. Not all methods work for all mushrooms. If you’d rather grow oyster mushrooms, check out this clever bucket method:

Unfortunately, I’ve found no evidence that this method works for portabellas. But I have found three methods that do:

How To Grow Portabellas Indoors

If you’re intimidated by DIY projects, the easiest way to grow your own portabella mushrooms is with a kit, such as this one

A kit typically has spores pre-mixed into its growing medium, so you can simply keep it in a cool, dark room, keep it moist, and enjoy a bountiful harvest in about a month. Instructions may vary from kit to kit.

But if you want to go the DIY route, there are many ways to grow delicious portabellas indoors. Here’s one way from Gardening Know How

To grow portabellas indoors, you will need:

  • A tray that’s about 4 by 4 feet (about 1 by 1 meter) and 8 inches (20 centimeters) deep
  • Manure-based compost
  • Portabella spores
  • Damp peat moss
  • Newspaper
  • Distilled water
  • A spray bottle

To Grow Portabellas Indoors, Do The Following: 

  1. Fill Your Tray With Compost.
A set of gardening tools

Begin by filling your tray with six inches (15 centimeters) of compost. 

  1. Add Your Portabella Mushroom Spores.

Sprinkle about an inch (2.5 centimeters) of portabella spores on top, mix them in a little, and gently pat the mixture down. 

  1. Wait Two Weeks.
A fuzzy, white film of mycelium
Image credit: flickr.com

Leave the tray in a dark room kept at 65-70F (18-21 C). Within two weeks, you should see a fuzzy, white film of mycelium.   

  1. Add Moist Peat Moss And A Layer Of Newspaper.
A moist peat moss
Image credit: flickr.com

When you see the mycelium, cover the compost with an inch (2.5 centimeters) of moist peat moss and top it off with a layer of newspaper. 

  1. Keep The Tray’s Contents Moist For Two Weeks.
Spray water bottle

Mist the tray with water twice a day for the next two weeks.

  1. If You Don’t See Any Mushrooms Yet, Wait A Little Longer.
Small mushrooms in soil

At the end of those two weeks, lift the newspaper to see if any mushrooms have begun growing. If they have, you don’t need the newspaper anymore. Otherwise, keep misting the tray daily and check under the newspaper after another week. 

It takes about 3-4 weeks for portabellas to fully grow as I explain in this article about how long it takes mushrooms to grow.

  1. Enjoy Your Mushrooms At Any Size.

Portabella mushrooms are edible at any stage. Feel free to harvest them while they’re tiny if you can’t wait! 

  1. You’ll Eventually Have To Start Over.

Over a two-week span, you can expect two-to-three flushes (harvesting periods). 

Unfortunately, mushroom cultures can’t go on forever. According to MyChampi, commercially-grown mushroom cultures only last for three-to-four harvest weeks. After that point, they grow less vigorously and become susceptible to diseases.

It’s not clear how long home-grown portabella cultures last, but kit manufacturers, such as this one, name a limit on how much you can harvest before the kit runs out of nutrients.

If your mushroom culture starts underperforming or looking sickly, the good news is that you can sterilize and reuse its compost medium for plants. 

In the instructions for growing portabellas outdoors, step 3 explains how to sterilize compost with sunlight.

How To Grow Portabellas Outdoors

To grow your own portabella mushrooms outdoors, you will need:

  • Four 4-foot by 8-inch (1-meter by 20-centimeter) wooden planks
  • Your preferred tools to build a raised bed
  • Manure-based compost
  • Cardboard
  • Black plastic
  • Portabella spores
  • Peat moss
  • Newspaper
  • Distilled water
  • A spray bottle 

To Grow Portabellas Outdoors, Do The Following:

  1. Make Sure It’s The Right Time Of Year.

You can only grow portabella mushrooms outdoors when temperatures are mild, within the range of 50F (10C) at night and 70F (21C) during the day. 

  1. Build A Raised Bed And Fill It With Compost.
Raised garden beds in the backyard

Building a raised bed is probably the best outdoor option because it gives you complete control over what you put in it. 

Gardening Know How recommends that the bed be 4 by 4 feet (about 1 by 1 meters) and 8 inches (20 centimeters) deep, filled with 5 to 6 inches (13 to 15 centimeters) of manure-based compost. 

  1. Sterilize The Compost And Order Your Spores.
Cover your soil bed with black plastic bags

It’s important to sterilize your compost before growing mushrooms in it, or else you might accidentally grow a wild variety!

To sterilize the compost, cover it with cardboard and black plastic. Over the next two weeks, the sun’s trapped heat will cook the compost, so you can know for sure what mushrooms you’ll be growing. 

Order your portabella spores  while you wait.

  1. Add The Spores To The Compost.

When two weeks have passed, remove the black plastic and cardboard. Add about an inch (2.5 centimeters) of the spores onto the compost and mix them in a little. 

  1. Wait Two Weeks For The Mycelium To Form.
A white film or Mycelium begins to form
Image credit: flickr.com

If conditions are right, you’ll see fuzzy, white mycelium in a couple of weeks.

  1. Add Peat Moss And Newspaper.

When the mycelium appears, cover the compost with an inch (2.5 centimeters) of moist peat moss topped with newspaper. 

  1. Keep The Bed Moist.

Twice a day for the next 10 days, mist the bed with distilled water. If you prefer little mushrooms, you’ll be able to harvest them very soon.

  1. Enjoy Button, Cremini, Or Portabella Mushrooms!
Button, Cremini, and Portabella Mushrooms
Image credit: botit.botany.wisc.edu

I’ll explain this in-depth in the next section, but these three mushroom varieties are actually the same species at different stages of growth. Portabellas are the most mature stage, but you can enjoy button and cremini mushrooms sooner.

  1. Recycle The Spent Compost

As I said in the indoor growing instructions, mushroom cultures can’t last forever. They remove nutrients from their growing medium until it can’t sustain them as well. 

Fortunately, your spent compost will still be nutritious for plants. Just sterilize it again by repeating step 3, so your plants won’t have any competition.

What Are Portobello Mushrooms?

A portabella mushroom is a large, dark-brown mushroom with a wide, relatively flat cap. It’s actually the same species as a button or cremini mushroomAgaricus bisporus. 

Basically, the only difference between them is their size when they’re harvested, with portabellas being the biggest of the bunch. 

However, Culinary Lore explains that a button mushroom won’t necessarily mature into a portabella. In reality, Agaricus bisporus mushrooms will only mature to this size and color in the second or third crop of your mushroom bed if they are not picked earlier.
Believe it or not, portabella mushrooms used to be too unpopular to sell well. In the 80s, mature Agaricus bisporus were marketed as “portabellas” to increase their popularity. 

It worked! In addition to button and cremini mushrooms, you may have encountered baby bella mushrooms — these are just creminis getting the same marketing treatment.

You might be wondering which is the correct spelling — portabella or portobello? Either is acceptable, although the Mushroom Council prefers portabella.

A beautiful portobello mushroom

Why Grow Them?

Growing any fungus is a fun and fascinating alternative to regular gardening, especially since it can be done in the dark. And when you grow edible varieties, you get to enjoy them at a better quality and price than you could find in grocery stores.

Growing portobello mushrooms at home is an especially fun choice for two main reasons:

  • You can enjoy three (culinary) mushroom varieties by harvesting the portabella species at different growth stages. 
  • Portabella mushrooms’ patty-like caps, which average six inches (15 centimeters) in diameter, are an ideal substitute for hamburger patties.

The Health Benefits Of Mushrooms

Besides being fun and delicious, portabella mushrooms are good for you. Mushrooms, in general, are low in carbohydrates, fat, and calories, while providing a modest amount of protein. Additionally, they provide about 15 vitamins and minerals, including:

B Vitamins

Mushrooms are high in B vitamins, such as niacin, riboflavin, and pantothenic acid, which work together to protect your heart. 

On its own, niacin is good for your digestive system and skin. Riboflavin is good for your red blood cells, and pantothenic acid aids your body’s nervous system and hormone production.

Mushrooms are also a good source of folate, which helps with red blood cell formation, cell growth, and cellular functions. 

Copper

Just one cup of cooked mushrooms can satisfy a third of your daily copper needs, which is great news for your bones and nerves. Copper also helps in the production of red blood cells, which deliver oxygen to your cells.

Magnesium

Inadequate magnesium intake has been linked to osteoporosis, diabetes, clogged arteries, high blood pressure, and strokes. According to the USDA, a cup of sliced, grilled portabella mushrooms contains about 16 mg of magnesium.

Zinc

Your body needs zinc to use as an enzyme catalyst, aid its immune system, heal wounds, synthesize proteins, and help with cell division. 

Portabella mushrooms are a modest source of this essential mineral. The daily zinc recommendation is 8 milligrams for women and 11 for men. 

A cup of grilled, sliced portabellas contains about .786 milligrams, which means they provide about 8 percent of the average person’s daily zinc needs. 

Potassium

Just one portabella mushroom can have more potassium than a banana! That’s good news because electrolytes, like potassium, aid your body’s blood pressure, nervous system, digestion, and heart rhythm.

Antioxidants

Mushrooms are high in antioxidants, such as selenium and glutathione, which may protect against cell damage, inflammation, and chronic diseases. 

Additionally, they’re an excellent source of ergothioneine. Research suggests that both glutathione and ergothioneine can slow aging.

Mushrooms May Preserve Brain Health

A recent study found a significant link between eating mushrooms and having a healthy brain. 

By tracking 663 seniors from 2011 to 2017, researchers discovered that the ones who ate over two cups of mushrooms per week were 50 percent less likely to develop mild cognitive impairment. 

Mild cognitive impairment refers to memory and language problems that don’t yet impair daily functioning. This condition often precedes Alzheimer’s disease.

The Mushroom Life Cycle 

You may be surprised to learn that fungi, such as mushrooms, are more closely related to people than plants! 

Though they can seem plant-like, fungi belong to a completely different kingdom. Rather than producing their own food through photosynthesis, they feed on organic matter.

The information below is mostly from this handy video:

It may be unnerving, but that organic matter isn’t always dead. Mushrooms come in two main varieties:

  • Saprophytes, which feed on dead organic matter. Portabella mushrooms fall into his more gentle category.
  • Parasites feed on living organisms, such as plants and insects. If you think your stomach can handle it, skip to 6:21 in the video above to see what cordyceps does to ants.

Mushrooms reproduce by releasing spores, which you may be breathing in right now. You know how your food grows mold if you keep it too long? This happens because your home is always full of fungal spores waiting to land and start a colony in the right habitat. 

When mushroom spores land in their preferred organic matter, they send out root-like structures called hyphae that form colonies as they search for nutrients and water. 

The networks they create are called mycelia. In the above video, GroCycle compares a mycelium to “an inside-out stomach” because it secretes digestive enzymes onto its food.

Life cycle of a mushroom
Image credit: emaze.com

The final stage in the life of a mushroom is reproduction, after which it dies. For a mushroom to reproduce, one mycelium has to meet another. It releases billions of spores into the air from underneath its cap and the cycle begins again.

Portabella Mushroom Serving Suggestions

If you’ve only enjoyed mushrooms on pizza, you might not know what to do with the ones you grow. Here are some delicious suggestions:

Knowing How To Grow Portobello Mushrooms Is Life-Changing!

Fresh portobello mushrooms are a treat to have on hand because their meaty flavor goes well in so many recipes. And with the money you save from growing portobello mushrooms at home, you can enjoy them more often! Whether or not you have a yard, you can grow food!

What did you think about my tutorial? Please let me know in the comments. If you liked, be sure to share it.

This article is mainly for DIY’ers, but don’t forget that it’s easier to grow mushrooms with kits such as this one. Kits generally come pre-assembled, so you can just keep them moist and wait to harvest their fresh, delicious mushrooms.

For more indoor gardening ideas, check out this other article. And if this tutorial inspired you to get into other types of gardening, you may enjoy this blog article on 17 essential gardening tools.

Last update on 2021-09-18 at 17:29 / Affiliate links / Images from Amazon Product Advertising API

1 thought on “How To Grow Portobello Mushrooms At Home: Our Complete Guide”

  1. In step 4 of outdoor growing instructions you state: “Add about an inch (2.5 centimeters) of the spores onto the compost”. That is being added to a 4 foot square bed. So I would need a small pickup truck full of spores, right? But you said in step 3 that I should mail order them! What is wrong here?

    Reply

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