Scientific name: Agaricus bisporus
Growing Portobello mushrooms involves a different type of growing style. Instead of using substrates like brown rice flowers or vermiculite, portobello mushrooms grow using a compost layer.
Required Supplies
Portobello Mushroom Spore Syringe
Growing Portobello Mushrooms with a Grow Bag
When growing portabello mushrooms, the easiest option is to buy a mushroom growing bag with a dung-based substrate. The bag comes complete with the growing medium inside the bag and requires no effort on your part except to open the box and then mist it with water regularly.
For your portabello mushroom kit, you will need the above syringe, as well as a grow bag here:
Important: If you want to grow using a mushroom grow bag, see our growing bag guide here!
Portobello Mushrooms Growing Guide
You can grow portabello mushrooms at home yourself with no kit. You need to purchase the above spores, but the rest is like regular gardening.
Portabello mushrooms can be grown indoors or outdoors.
Growing Portobello Mushrooms Outdoors
If you are growing outdoors, be sure that daytime temps do not exceed 70 degrees F. (21 C.) and that night temperatures don’t drop below 50 degrees F. (10 C.). If you want to start your portabello mushroom growing outdoors, you need to do a little prep work:
- Build a raised bed 4 feet by 4 feet (1 x 1 m.) and 8 inches (20 cm.) deep.
- Fill the bed with 5 or 6 inches (13-15 cm.) of well-seasoned manure-based compost.
- Cover this with cardboard and attach black plastic to cover the bed. This will induce solar radiation, which sterilizes the growing medium of contaminants. Keep the bed covered for two weeks.
- Once the two weeks have passed, remove the plastic and cardboard. Take the spore syringe, put a few ML of the liquid on top of the compost, and then lightly mix.
- In about two weeks, you will see a white web (mycelium) appear across the surface of the medium. It looks like white mold; this is how mycelium appears. This indicates your spores are growing.
- Add a 1-inch layer of moist peat moss across the top of the growing medium. Then, put newspaper over the top. Mist daily with water and continue misting twice daily for 1-2 weeks.
- Your mycelium will begin to produce pinning mushrooms.
Growing Portabello Mushrooms Indoors
To grow your mushrooms inside, you will need a metal tray to grow in, dung-based compost, peat moss, and newspaper. The tray is best at 8 inches (20 cm.) deep and 4 feet x 4 feet (1 x 1 m.) or at least very close. This indoor process is very similar to outdoor growing!
- Keep the room between 65 and 70 degrees F (18-21 C).
- The tray is best at 8 inches (20 cm.) deep and 4 feet x 4 feet (1 x 1 m.) or at least very close.
- Fill the tray with 5 inches (15 cm.) of the seasoned dung or manure-based compost, add 1-2ML of your spore syringe, then mix the compost and lightly press down. Put the tray in the dark until you see the white mycelium web growth.
- Lay a layer of damp peat moss down and cover with newspaper—mist twice daily for two weeks.
- Remove the paper and check on your mushrooms. If you see little white heads, remove the newspaper permanently. If not, replace the newspaper and keep misting for another week.
- Once the paper has been removed, mist daily.
- Now, your mushrooms will be growing rapidly. Harvest to suit your size preference. You can grow portobellos indoors year-round with this method. You can get two to three separate sets of mushroom flushes from the same mycelium over two weeks.
Congratulations. You have completed the guide! Enjoy your delicious homegrown portobello mushrooms.
