How to Fertilize Mushrooms in the Dark With Manure

Use a shoe box or plastic bin as your mushroom box. Mix organic compost or topsoil with well-rotted manure as your growing foundation, and fill the box three-quarters full. Mushrooms do best in rich, loose foundations that retain moisture.

Inject a mushroom culture into the foundation, per manufacturer instructions. Mushroom cultures (available and home and garden shops and specialty manufacturers) contain mushroom spores, which grow to become the mushroom colony. The mushrooms themselves are the fruit of this colony. Choose button, morel, oyster and porcini mushrooms for this particular growing foundation.

Spray the growing foundation with water to moisten the top 2 inches of soil. Mushrooms require consistent moisture, but can't grow in soggy soils. Put the box in an empty cupboard or drawer with a heating pad. Keep the heating pad at 70 degrees F and give the mushroom culture three weeks to take root.

Reduce the heating pad to 55 degrees F after three weeks to encourage mushroom growth. Cover the existing soil with another 1 to 1 1/2 inches of topsoil/manure mix. Spray the soil to wet it, then cover the box with a wet cloth. Spray both soil and cloth when they dry.

Allow three to four weeks for mushroom sprouting, and continue your care until harvest. Harvest the mushrooms when the caps separate from the stems and spread out.