7. Mushroom compost.
Many people think compost is all about fertilizer, but sometimes compost is nutrient-poor but still good for the garden. Such is the case for mushroom compost, the mushroom-growing substrate after mushrooms have grown and used up all of the nitrogen. Mushroom compost is made up of wheat straw, dried blood, horse manure, ground chalk and other things. Added to the soil, it increases tilth. Because of the chalk, it tends to be on the alkaline side, so don’t use it for acid-loving plants such as weigela or blueberries.