Growing Portobello Mushrooms at Home: Some Simple Tips for You

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.

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.

Growing Portobello Mushrooms Indoors

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.

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.


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.



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.

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.

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.


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.