How To Grow Portobello Mushrooms (From Stem & Store Bought)

Do you get excited by the thought of growing your own food from the comforts of your home? If yes, then this article is for you. Today, we'll be showing you how to grow portobello mushrooms from store bought, and from stems at home.

But first, what is Portobello mushrooms?

Portabello mushrooms (also known as Portabella mushrooms) are rich meaty mushrooms that are distinguished by their thick, flat, brown cap and white stem.

They are an edible plant fiber that is extremely rich in Vitamin B, vitamin D, copper, selenium, potassium, phosphorus, vitamin B6, and niacin, antioxidants, fiber, and phosphorus.

This mushroom is cooked and popularly served in restaurants and homes around the world. It's commonly found worldwide in fields and grassy areas mostly during the rainy season and sometimes in spring.

Geography & History of Portobello Mushrooms

You probably think that mushrooms generally does not have a place of origin. Well, it will surprise you to know that portobello mushrooms do. They originated from Italy and have been growing wildly a long time before they were cultivated.

The first record of this mushroom was in 1707, which was discovered by a French botanist Joseph Pitton de Tournefort.

Then in the 1980s, Whole Foods stores discovered that Natural foods such as the portobello mushrooms had become high in demand which prompted it to be widely marketed at that time.

Today farmers and gardeners grow Portobello mushrooms and make them widely available at farmers' markets, grocery stores, and supermarkets in Europe, Asia, North America, Australia, and West Africa.

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How Do Portobello Mushrooms Grow?

To grow portobello mushrooms, you need to understand that they are not grown from seeds just like other mushroom species, but are grown from spores.

Spores are tiny unicellular or single-celled reproductive bodies that enable the fungus to grow.

Since spores don't contain chlorophyll to make their own food in order to germinate, they rely on substances such as straw, sawdust, decayed plants, grains, wood chips, water and so on, to form organic matter for nourishment.

When the spores mix with the organic matter and its nutrients, it is referred to as spawn. The spawn supports the growth of mushroom roots called mycelium.

Like the mushrooms, the mycelium first appears before anything that looks like mushroom sprouts through the growing medium. They are very tiny, whitish and hair-like in structure.

In the process of growing portobello mushrooms, there are some factors to be considered. These factors include soil conditions (growing medium), temperature, moisture, and humidity.

Now, let's discuss them below one by one:

Soil conditions (Growing medium)

Portobello mushrooms will thrive best on a compost-rich soil. Compost is a mixture of yard waste, such as grass clippings, weeds and branches, animal droppings or manure and kitchen wastes like vegetable scraps, eggshells, and other organic materials.

This matter is kept warm and moist until it depreciates into a rich, loamy soil-like material hence a growing medium.

Portobello mushroom growing temperature

Talking about portobello mushroom growing temperature, it's worth noting that mushrooms grow faster at warmer temperatures and slower at colder temperatures. Mushrooms grow at temperatures between 60 to 74 degrees Fahrenheit.

Constant temperatures higher than 74 degrees Fahrenheit usually prevent mushrooms from growing, and temperatures over 86 degrees Fahrenheit, over a certain period can kill the mushroom mycelium (the fungus).

Cooler temperatures below 55 degrees reduce its growth rate or cause it not to grow at all.

Moisture and humidity

Portabella mushrooms need water for their fruit to grow. Mushrooms usually do not have skins, so they can lose water to the atmosphere very quickly. That is why they need to grow in highly humid conditions.

If the humid condition of their environment is too low, their cells lose water faster which means immature mushroom will dry up and die.

And if the humid conditions are too high, it will be just like submerging the body of the mushroom in water which is comparable to drowning.

No oxygen can be exchanged, anaerobic bacteria (bacteria which do not need oxygen to thrive) build-up, and the mushroom is choked to death.

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Where to Grow Portobello Mushrooms

To get the best quantity and quality of portobello mushrooms, they have to be grown in cold, dark, moist environments.

When growing portobello mushrooms at home, storerooms or basements are ideal as they require just a small area of space and a little reflection of light to bloom.

Additionally, Portabella mushrooms can be grown all-year-long if grown indoors since the temperature can be controlled indoors. However, they can also be grown outdoors under the right temperatures.

Growing Portobello mushrooms indoor is usually similar to the process of growing them outdoors.

You just have to make sure the growing medium used is sterilized for the mushrooms. The overall process might take a bit longer than if done indoors.

How To Grow Portobello Mushrooms Indoors

Here are the steps of growing portobello mushrooms indoor:

1. Build a tray

In order to grow portobello mushrooms, you will need to build a tray out of either scrap wood or fresh planks, which can be purchased at lumberyards and online stores.

The frame needs to be about 20 cm deep and at least 15 cm long. Then, make a rectangular shaped bed by nailing the wood together.

Apart from assembling a tray, another option is to purchase a mushroom growing kit from a gardening store or an online store. It includes all the components you will need to grow portobello mushrooms.

2. Fill the bed with manure-based compost mixed with mushroom spores

Find a way to get compost manure, either you purchase it from the garden center or any online store, or you could just make it yourself.

Then pour it into the bed until it is 15 cm deep. Mushroom spores can also be purchased on online stores such as Amazon, and may also be found at some gardening stores.

Once you have them, with a pair of rubber gloves on, add the spores onto the compost, then gently mix it in about 2.5 cm deep. Then Press down on the compost when you're finished.

However, you may try other organic compost products in place of manure-based compost. Now that you already know how to get portobello mushroom spores, let's move to the next step.

3. Add peat moss and water regularly

The next thing that you need to do is to place a layer of peat moss and cover it with a  newspaper. You need to water the tray twice every single day for a couple of weeks.

Once done, you can start removing the paper in order to check if the mushrooms already have little white head sprouting out. If you don't see any, you can put the newspaper back and continue to water it for a week.

4. Wait to harvest

After a while, the little whiteheads become matured portobellos, and once you have removed the newspaper, you can start harvesting them immediately.

You also have the option to wait for them to grow bigger if you want larger mushrooms. Just make sure to keep it in a room that has a temperature of about 65 to 70 degrees Fahrenheit and continue to add water.

How To Grow Portobello Mushrooms From Store Bought

Can you grow portobello mushrooms from store bought? Yes, you can grow store bought mushrooms, and they’re easy to propagate. But in order to get make them grow, you will have to choose fungi from organic sources.

That said, growing store bought portobello mushrooms from the ends requires just a suitable fruiting means and the best growing environment.

When it comes to growing portobello mushrooms from store bought stems, the best size to go for stems is ¼ inch (6 mm.). You can layer your medium with a cardboard box, a plastic bin, or paper bags.

To do this, simply place some of the straw or any other moist material at the bottom of the medium, then add the mushroom end pieces. After that, do another layer until the pot is full.

How To Grow Portobello Mushrooms Outdoors

• Make a garden bed from conventional building materials, most especially wood. It should be about 8 inches deep and four-by-four feet in dimension.
• Fill the constructed bed with compost.
• Cover the surface of the bed with old newspapers and the bed with black plastic to enable solar radiation in order to sterilize the bed. Then leave it for about two weeks.
• After two weeks, remove the black plastic and newspaper coverings, and then sprinkle the spores across the compost and work them in by gently mixing. Then leave it for another two weeks.
• In two weeks' time, the mycelium will start to emerge across the surface of the bed. Add a layer of damp moss across its surface, and cover it with the newspaper.
• Water daily for ten days, then harvest when the mushrooms are fully matured.

How To Harvest Portobello Mushrooms

When you are growing portobello mushrooms, it is essential to note that if you harvest them 3-7 days before they are fully matured, you are just harvesting crimini mushrooms.

Therefore ensure that you follow the steps above and wait through its growth stages.

To know if they are fully grown, check if their caps have grown flat instead of curled. Portobellos reach maturity when their caps are about 4 to 6 cm in diameter.

Dig them out of the compost with your hands, then clean them with a damp paper or cloth, then store them in a dry container in a cool place or refrigerator.

Continue to add water to the compost until new mushrooms sprout up. After the first batch is harvested, continue to water it regularly and add a new layer of the newspaper when you see white streaks form again.

And by following these steps repeatedly, you will be able to harvest up to three batches of mushrooms.

Frequently Asked Questions

Are portobello mushrooms easy to grow?

Yes, portobello mushrooms are pretty much easy to grow. You can make the growing process easier by buying a growing kit. Or just put together a planting bed and plant your portobello spores in it.

Remember to keep the soil damp and at the right temperature, whether you’re growing your portobello mushrooms indoors or outdoors.

What is the difference between Portobello and portabella mushrooms?

Both portobello and portabella mushrooms are the same thing. The use of the two words “portobello vs portabella” is basically all about marketing brand.

Where do portabella mushrooms grow naturally?

In terms of where portobello mushrooms grow in, portobello mushrooms can be grown indoors in a tray or container, and you’ll also need a compost, newspaper, and peat moss for healthy growth.

It also grows outdoors following pretty much the same process.

Can you grow portobello mushrooms in coffee grounds?

Yes, you can grow portobello mushrooms in coffee grounds. In fact, coffee grounds are a fantastic growing material for mushrooms that are grown at home.

Before planting the portobello mushroom, endeavor to moisten the grounds, spreading them into your growing tray or pot. Then add your spores to sawdust and use your hand to mix them into the top 1 inch of the coffee layer.

What's bad about portobello mushrooms?

Just like every other mushroom, portobello mushrooms contain a toxin, hydrazine known as carcinogenic compounds in raw form. However, this chemical is heat-sensitive and disappears upon exposure to heat.

Is it safe to eat raw portobello mushrooms?

Yes, it is very safe to eat portobellos raw; however, cooking them will make them tender and enhances their flavor.

What is the best substrate for portobello mushrooms?

The best substrate to use for portobello mushrooms is straw mixed with horse manure. But they also thrive well in nutrient-rich compost.

How do you pick a portobello mushroom?

When picking portabella mushrooms, look out for caps that are uniform in color (not spotty) and are firm. And for a stronger earthy taste, go for mushrooms with thick veils and has a dark color.

Do portobello mushrooms need light to grow?

Like every other mushroom, portobello mushrooms are non-green, which means that there’s absence of chlorophyll in them.

The absence of chlorophyll also means that portobello mushrooms do not make their own food; thus, there is less need for sunlight.

Can I grow baby bella mushrooms?

And can you grow portobello mushrooms? The answer is Yes, you can grow your own baby bella mushrooms.

You can do this by either buying a growing kit or by starting the process on your own. Either way, you will still need to purchase the mushroom spores.

How long does it take to grow portobello mushrooms?

It basically takes about 3 to 4 weeks for portabella mushrooms to fully grow to maturity.

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Conclusion | How to Make Portobello Mushroom Spawn

Growing portobello mushrooms is easier than you think if you follow the above steps accordingly. However, if you don't want to go through the rigors it entails, you can simply purchase a growing kit.

If you choose to grow portobello mushrooms either indoors or outdoors, ensure that the growing medium or soil is damp and at the right temperature with adequate manure.

Soon, you will have tasty mushrooms to chop up into a Salad or any other food delicacies you want to use it for.

I hope this article has given you adequate information on how to grow portabello mushrooms, according to where you prefer to grow them.