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Growing It Local > Garden Wiki > Potting Soil

Potting Soil

Potting Soil is used in containers when starting seedlings to be planted out in the garden later or for pots that will grow plants to maturity. Potting soil mixes purchased at garden centers are usually not ideal for vegetables. They often contain decomposed bark and wood chips that are better suited to indoor ornamental plants.

Potting Soil Recipes

Organic Gardening Magazine Soil Mix Recipes

Potting Soil Ingredients

Garden Soil

Garden soil can be sterilized by heating it to 180 degrees. Some gardening experts recommend sterilizing garden soil before adding it to a potting mix while others don't.

Sphagnum/Peat Moss

This is used as a soil conditioner to increase the soil's capacity to hold water and nutrients. It is harvested from Sphagnum Moss bogs and is acidic.

Coconut Coir

This is made from coconut hulls. It is used as an alternative to Sphagnum/Peat moss as a soil conditioner to increase the soil's capacity to hold water and nutrients. It is PH neutral in contrast to Sphagnum/Peat Moss that is acidic.


Vermiculite is a mineral that looks similar to mica when mined, but expands when heated in the manufacturing process. It is mixed in heavy, clayey soils to create air channels and is mixed in sandy soils to help the soil hold water. Vermiculite can soak up 3 to 4 times its volume in water. It provides more water retention and less aeration than perlite. It is commonly used in Square Foot Gardening.


Perlite is a volcanic glass. When heated in the manufacturing process, it expands like popcorn into a lightweight, porous material that looks like white granules and is sometimes mistaken for tiny plastic foam balls. It is used in potting soil to improve aeration and drainage. It provides more aeration and less water retention than vermiculite. Because it is very light, it tends to float to the top of a pot when it is watered and may blow away outdoors.


Pumice is a volcanic rock that is formed when lava cools quickly, forming a highly porous, light weight rock. Its benefits are similar to perlite, but it is heavier, making it less likely to float to the top of a pot or to blow away outdoors.

Rice Hulls

Rice hulls increase aeration without the tendency to float to the top of the pot like perlite. They provide silica.


Sand is used to reduce compaction and increase drainage.


Compost is organic matter that is partially decomposed. It is a soil conditioner and provides nutrients and humus.

Well-Rotted Manure

Well-rotted manure adds organic matter and nutrients. Manure from horses, pigs, cattle, sheep, chickens, turkeys, rabbits may be used. However, commercial steer manure should be avoided or used only in small quantities because it is high in salt. Horse manure may contain live weed seeds, including Bermuda Grass, unless it has been composted at a high temperature.