Indoor houseplants should not be grown in the same type of soil used in your garden beds. Soil dug up from the ground and put into a pot with an indoor plant will almost always be lacking in the organic matter needed to lighten its structure enough to keep it from crusting over. Use a commercially available potting soil that contains the right proportion of soil and organic matter to successfully grow indoor potted plants.
Potting soil specially formulated for house plants contains sterilized soil. The soil has been heated to 180 degrees F. for at least 30 minutes to kill weed seeds and disease organisms. It is usually the largest component of a potting-soil mixture.
Sphagnum Peat Moss
Partially decayed remains of ancient plants, sphagnum peat moss is naturally sterile and free of weed seeds. It holds many times its weight in water, which keeps the soil in potted plants from drying out too quickly. Peat moss also improves the texture of the soil, creating air pockets with its large fibers. Air pockets facilitate root growth and allow water to drain readily, eliminating soggy, water-logged soil.
Made of volcanic rock that has been heated until it explodes, perlite is added to potting soil to provide bulk, thereby lightening the overall weight of the potted plants. It also improves the texture of the soil, creating air spaces for roots to grow and water to drain rapidly.
Coarse Builder's Sand
Added to soil mixtures for seed starting, growing orchids, cactus and succulents, coarse builder's sand improves the texture of the soil as well as its drainage while creating air pockets. It does not hold many nutrients, which is best for cactus and succulents, plants that prefer practically infertile soil.