Growing Portobello Mushrooms at Home: Ultimate Step-by-Step Guide

Portobello mushrooms are identified by brown caps, meaty flesh and an intense flavor. They contain a number of nutrients such as vitamin B, protein, minerals, and fiber. While providing numerous nutrients, the mushrooms are low in calories and fat and are cholesterol free; therefore they are a perfect alternative to meat and can be added to any diet. Vegetarians and those who want to lose weight would find Portobello mushrooms a great addition to a healthy diet. Wondering how to grow Portobello mushrooms at home? This is something you can definitely do! There are a few simple steps to follow, and you will be well on your way to growing Portobello mushrooms.

What are Portobello Mushrooms?


Portobellos are members of the agaricus bisporous family, a kind of edible mushrooms first known to have existed in Europe and North America. Portobello mushrooms are actually the mature form of common crimini mushrooms, or button mushrooms, which are often harvested while immature. Once the young crimini mushrooms have grown up to 4 to 6 inches in diameter, they are known as portobello mushrooms.

When it comes to portobello history, it is said that portobello mushrooms were first grown by the Americans with spores from Italy. The New York Times first brought crimini and portobello mushrooms to the public’s notice in the mid 1908s. Since then, the knowledge on how to grow portobello mushrooms has spread worldwide and people have practiced growing portobello mushrooms for decades.

There used to be a debate about whether the name portobella or portobello is more correct. In fact, both are accepted and the use of which name to use is simply a marketing brand issue. For the name portobello itself, there are several assumptions for its origin. The mushrooms could have been named after a town in Italy, or after Portobello Road in London which is popular for its valuable antique shops and fashionable stores. Another assumption for the name is the TV show Portobello. No matter where the name originates from, portobello mushrooms have become a hugely popular ingredient in various dishes such as grills, soups, salads or sandwiches.

Shape, size, taste

Identified by their brown caps, meaty flesh and intense flavor that remains intact even after cooking, portobello mushrooms are said by Wades Whitfield of The Mushroom Council to have become a phenomenon in the food business. It is not an exaggeration to say that this mushroom has gone from being practically unknown to becoming a gourmet item.


Growing portobello mushrooms in the past was not a good investment as there was no market for them. However, their meatier flavor really sets portobello mushrooms apart from crimini mushrooms, and that has been the key to the rapid gain in popularity of these mushrooms. Growers started to switch from growing crimini to growing portobello mushrooms.

Growing portobello mushrooms is not a big deal for those who are experienced with crimini mushroom cultivation as one must simply let the crimini mushrooms mature for another 3 to 7 days and what they then harvest will be portobellos. Although white button mushrooms are still the more popular of the two, portobello mushrooms have made inroads into the market and the consumption keeps going up all over the world.

Biological characteristics

As a kind of fungi, mushrooms in general, or portobello mushrooms in particular, are distinguished from plants by the fact that they don’t have chlorophyll and cannot make their own food via photosynthesis. Plants start from seeds and grow from soil, while mushrooms start from spores which germinate and spread widely into hair-like mycelia while developing on substrate in commercial growing or on decaying materials in nature. Cool, dark places with high humidity are best for growing portobello mushrooms. Temperature greatly affects the outcome of the mushroom harvest, so it should be kept stable and the humidity kept between 65% to 80%. It is said that a temperature between 60°F to 70°F is ideal for mushroom fruiting and the range from 63°F to 68°F is best for both the quality and quantity of portobello mushrooms.

Nutritional value

Humans need basic nutrients such as fat, carbohydrates and protein on daily basis. Portobello mushrooms provide a balance of carbs and protein with low fat. It is recommended that men should consume 56g of protein a day and women 46g, and both should go for 130g of carbs per day. Just 100g of portobello mushrooms will supply your body with over 3g of protein, 4 ½g of carbs and just ½g of fat. This means that adding portobello mushrooms to your daily diet helps to balance your protein and carbs intake while reducing your meat consumption.


Fiber, a key element in regulating cholesterol and blood sugar is found in moderate amounts in portobello mushrooms. Specifically, 100g of portobellos have just over 2g of fiber. The calories that a 100g of portobello mushrooms contain about is just 30, a pretty low level. That’s why they are listed as low-energy density foods.

Like a variety of other fungi, portobello mushrooms are a good source of vitamin D. The amount of vitamin D preserved in portobello mushrooms depends on the amount of exposure to ultraviolet light. Some growers intentionally raise the time that their portobello mushrooms are exposed to ultraviolet light on purpose in order to increase their vitamin D content. B vitamins are also found in moderate amounts in portobello mushrooms, so having them together with green vegetables, fish and whole grains should supply your body with an adequate amount of B vitamins. Copper, selenium, potassium, phosphorous, and sodium are among the minerals that can be found in portobello mushrooms as well.

Health benefits

So far we have learnt about the nutritional facts of portobello mushrooms. So just how beneficial are they to our well-being? The remarkable benefits that portobello mushrooms are well-known for are fighting against cancer, combatting inflammation and protecting the immune system.

The anticancer properties of portobello mushrooms are thanks to the presence of phytochemicals that positively affect living and dead cells, metabolism and immune responses. In particular, portobello mushrooms are meat-free sources of CLA, an ingredient that helps to prevent cancer cells from proliferating.

A low level of ergothioneine (ERGO) is associated with a high risk of chronic inflammatory diseases. However, portobello mushrooms are a rich source of the ERGO that humans cannot synthesize by themselves. Consuming mushrooms are the best way to supply our bodies with the element.


For those who wish to lose some weight, portobello mushrooms are a great choice for their low calorie content. You may consume a large volume of portobellos without worrying about going over your daily calorie allowance. For vegetarians, ortobello mushrooms are an ideal alternative to meat for their protein supply.

Vitamin D helps to facilitate normal immune system function, and bone and teeth growth while B vitamins are essential for a healthy metabolism, nervous system, and for maintaining healthy skin, hair and eyes. Minerals such as phosphorous, potassium, copper, and selenium help to strengthen bones and keep blood vessel healthy. Consuming portobello mushrooms could bring you all these health benefits.

How to Grow Portobello Mushrooms: Ultimate Step-by-Step Guide

Now that you have gained some basic information about portobellos, you may be tempted to rush to the nearest grocery store to shop for this fresh meaty flavored mushroom. It’s no big deal to purchase portobello mushrooms for your diet, but have you ever thought of growing them at home? If you wonder how to grow them, the following paragraphs will help you find out how. If you are eager enough to grow this mushroom for yourself, the practical steps below will be a helpful guide to see you through the cultivating process.


Growing Portobello mushrooms is quickest and easiest when you buy a kit including everything needed to grow the mushrooms. The kit already has spores grown in the medium, and all you need to do to harvest the mushrooms is follow the instructions included with the kit. Keep them in a cool, dark place, keep them moist, and wait approximately a month to harvest the mushrooms. However, if you would like to know how to grow Portobello mushrooms completely from scratch, there are two methods you can choose between – growing them indoors, or growing them outdoors.

Step 1: Material Preparation

Firstly, you will need to prepare the trays that the mushrooms will be planted in. These should be 4 feet wide, 4 feet long and 8 inches deep. You will also need some compost, peat moss and newspapers. This is the medium you will use to grow the mushrooms in. Unlike other vegetables that grow from seeds, mushrooms belong to the fungi family, and grow from spores. You can look for Portobello mushroom spores at local gardening centers or buy them online.


Step 2: Planting The Mushrooms

Once you have gathered the necessary materials, you can fill up the trays with manure compost – approximately 6 inches of it. Then sprinkle the spores on the compost, mix them in and pack the compost down slightly. Put the trays in a cool, dark place and wait for a white growth to develop on top of the compost. As soon as you notice the white growth, place a layer of peat moss over it, and a layer of newspapers on top.

Step 3: Care

You do not need to do much to take care of the mushrooms. Trays with a small amount of white growth should be misted twice daily for a couple of weeks. The temperature should be monitored and kept between 65◦ F and 70◦ F. Remember the environment should be just moist, not soaking wet. Once the white heads have grown a little bigger, you can remove the newspapers. If they have still not grown taller, keep misting them for another week until you notice growth.

Step 4: Harvest

Portobello mushrooms can be harvested as soon as the newspapers are removed, however, you might want bigger mushrooms. If you do want them to grow bigger before harvesting them, continue to mist and wait for the mushrooms to grow to your preferred size. They are best if they are harvested when the caps are still a little curved down, rather than flattened. Indoor growing allows you to grow mushrooms all year round because the temperature and moisture can be monitored.


Growing Portobello Mushrooms Outdoors

Growing Portobello mushrooms outdoors differs little from growing them indoors. However, you do need to pay more attention to maintaining the correct temperature and sterilizing the materials. The temperature that the mushrooms are exposed to should not go over 70◦ F or fall below 50◦F. You will need the same materials you needed for growing mushrooms indoors. Additionally, you will also need cardboard and black plastic. Now you can begin growing your mushrooms outdoors.

Step 1: Raised Beds

For indoor growing, we used trays to contain the medium that the mushrooms grow in. When growing the mushrooms outdoors, you will need to raise a bed to grow the mushrooms in. The bed should be at least 4 feet in length, 4 feet wide and 8 inches deep. If your outdoor space allows for wider and longer beds, you can extend them to 6 x 8 feet. You can create the raised beds using logs, woods, or concrete blocks. Once you have made the beds, fill them with seasoned manure compost up to 6 inches, the same as you did with your indoor trays. However, you will need to cover the compost with cardboard and then black plastic that has been fastened to the edge of the bed for 2 weeks. This will create a solar radiation effect, which will help to sterilize the soil.


Step 2: Sprinkle Spores and Add Peat Moss

After two weeks, you can remove the plastic and cardboard, and sprinkle the spores over the compost. Then mix the spores into the compost. As the white growth emerges, add a one inch layer of moistened peat moss to the top of the bed and cover with newspapers. Mist the mushrooms for twice a day for 10 days. Make sure it is not too wet as this could result in mosquitoes. Once you see the white heads have developed, remove the newspapers and continue to mist for the next 10 days with distilled water.

Step 3: Harvest

The mushrooms are best harvested when they are about 5 inches in diameter. However, you can harvest them when they are smaller or larger than this, depending on your preference. It is possible to get 2 to 3 batches of Portobello mushrooms over about two weeks before you need to replace the spores with new ones. To ensure a constant supply of mushrooms, you can grow a few batches of the mushrooms in intervals.


Caution: Growing Portobello mushrooms outdoors comes with the danger of accidentally picking poisonous (or even deadly) mushrooms. Be careful of parasol-shaped mushrooms, especially bright colored ones; as they are not Portobello mushrooms, but a poisonous species. Wrinkled brown mushrooms with irregular caps are also not Portobello mushrooms, but are known as “false morels”, so be sure to avoid these. Also ensure that you pick whole, fresh, firm Portobello mushrooms. Avoid decayed mushrooms or ones that are damaged by insects or animals. Portobello mushrooms should be round, brown puffballs with a thick stem and distinctive gills. Ensure that these are the mushrooms you are picking!



Now that you have all the information, growing Portobello mushrooms is not that difficult, right? You just need to grow them indoors in a tray or outdoors in a raised bed. Within a month, you will have the first fresh Portobello mushrooms in your kitchen. They are perfect for roasting or grilling. Not that you know how to grow Portobello mushrooms, enjoy making this deliciously flavored mushroom a part of your diet.

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