How To Grow Portobello Mushrooms Without A Kit. Spray the newspaper or cloth regularly for about 2 weeks, until the white buttons of the mushrooms begin to appear. Cover your growing tray with newspapers or with a cloth to retain the moisture.
Portabella mushrooms grow in temperatures no higher than 70 and no lower than 50. A spot under the sink, your basement, or any location in your home that can provide dark and humid conditions, is ideal for growing mushrooms. Mix the spores properly with the compost.
If you choose to grow your portabellas outdoors, leave your planting bed in direct sunlight for a fortnight.
On the other hand, if you want to grow them yourself, it is important to purchase portobello mushrooms spores to make the process easier. Your portabella mushrooms will be ready soon! However, the thing is that as mushrooms grow, their temperature needs changes. Along with the dark and humid location, the temperature is another important factor.