Portabello mushrooms have a flat cap and dark color once they mature. They are the biggest in size of all the cultivated mushrooms, growing more than six inches across. They have a distinctive, hearty taste and are popular in many dishes. They can be grilled, fried, baked, boiled or sauteed. Vegetarians use them as a meat substitute because they are the perfect size for a "burger." Growing portabello mushrooms at home is convenient because you will have as many of the mushrooms as you want. The best way is to use a growing kit, indoors or out.
Get a portabello mushroom growing kit from a plant nursery or online company. The kit should include spores and nutrients such as casing soil, straw substrate and grain substrate to grow the mushrooms at home.
Choose an outdoor planting location with a semi-soft soil. Portabello mushrooms do best in a mild climate. You can also use the kit to grow the mushrooms indoors.
Dig holes outside that are half an inch wide and a quarter inch deep. Each hole will house a couple of mushrooms.
Combine the spores and nutrients with the displaced soil. Follow the instructions that came with the kit. Place the mixture in each hole until they are filled. Watch the growth for two weeks, and add additional nutrients if the mushrooms are slow to sprout. You should notice baby mushrooms at the two week mark.
Grow portabello mushrooms indoors if preferred. Put the spores in the appropriate spot in the container.
Fill the container with water to the mark indicated. Portabellos do not grow well with chlorinated water, so tap water must sit out, uncovered, overnight so the chemical can dissipate.
Expect two or three harvests per portabello kit. A harvest is called a flush. It takes most kits about two weeks to produce a flush. Each kit will result in 3 lb. to 6 lb. of portabello mushrooms over three months.
Remove the mushrooms from the soil once you notice the root is above the dirt. Cut them out with shears.
Run water over the mushrooms to clean them of dirt. Put them in a plastic bag, and keep them in your refrigerator. The growing kits can be used again.