Can plants grow without soil? Yes! Indoor plants love soilless potting mixes. If you\u2019re new to container gardening or want to know why you keep seeing \u201csoilless mix\u201d on bags of potting \u201csoil,\u201d we\u2019ve got the dirt on this strange mixture.<\/p>
A soilless potting mix contains primarily organic materials that provide a home in which your plant roots can grow and receive nutrients. The end result? You end up with a healthy, strong plant.<\/p>
\u201cOrganic materials?\u201d you may ask. \u201cI thought soil was an organic material?\u201d Actually, organic<\/em> materials come from living things, while inorganic<\/em> materials usually come from the ground (like rocks) and do not consist of plant or animal (living) materials. <\/p> Therefore, soil is primarily inorganic<\/em> because it is composed of about 90% inorganic materials<\/a>, such as silt, clay, sand, and gravel. The other 10% or so is organic material<\/a>, usually in the form of decomposed matter like leaves, feces, and other plant debris. Conversely, soilless potting mixes are primarily composed of organic matter with a few inorganic components, namely perlite or vermiculite.<\/p> As you can see, a soilless potting mix will be quite different from the soil outside your front door.<\/p> Here\u2019s a quick breakdown of ingredients you may see in store-bought soilless potting media:<\/p> \u2713 Peat moss<\/a> Whether you\u2019re new to gardening or have been planting for years, you may not know exactly where these components come from. Here\u2019s the inside story on the ingredient<\/a> list for your favorite soilless potting mix:<\/p> Peat moss:<\/strong> Peat moss<\/a> is a natural product that is extracted from peat bogs (usually from Canada). It holds moisture well but also repels water (hydrophobic<\/a>). Experts recommend wetting this material on its own before you add in other elements of your mix. (Some peat moss comes with a wetting agent to help it absorb water more easily.) Peat moss is used to make the soilless mix lighter in weight or to increase its water retention ability.<\/p> Coco coir:<\/strong> Also called coco peat, coco coir is made from the outer hulls of coconuts (coconut husks). It is usually sold compressed in a \u201cbrick\u201d form that you rehydrate in water before adding to your mix. It is often used as a replacement for peat moss in soilless mixes. It holds water and aerates the soil at the same time. Some say it\u2019s more environmentally friendly<\/a> than peat moss. <\/p> Bark:<\/strong> A by-product of the forest industry, bark adds aeration to soilless mixes. If you buy (or make) a soilless mix specifically for orchids, you\u2019ll notice that it includes more bark<\/a> than standard soilless mixes to provide the extra aeration orchids require. Large pieces of bark<\/a> increase aeration but decrease water retention.<\/p> Vermiculite:<\/strong> Vermiculite is a silicate mineral<\/a> that is related to mica. When heated, it expands into an accordion shape and can hold air, water, and nutrients in between these layers.<\/p> Perlite:<\/strong> When you see perlite, think \u201cpop rocks\u201d (like the candy), because that is essentially what perlite is. Perlite is formed when volcanic rock is ground and heated to a high temperature. The result is that it expands from four to 20 times<\/a> its original size. Perlite helps the mix to drain well and helps air to circulate throughout.<\/p> Worm castings:<\/strong> Worm castings (AKA worm poop) are used as a fertilizer in some soilless mixes (mostly potting mixes rather than seed starting mixes). These castings<\/a> add nutrients and good bacteria that strengthen container plants.<\/p> Soilless mixes and topsoil are not<\/em> interchangeable. Here are a few of the differences between the two:<\/p> Soilless Mixes<\/span><\/h3>
\u2713 Coconut coir (AKA coco peat)
\u2713 Compost<\/a>
\u2713 Vermiculite
\u2713 Perlite
\u2713 Bark<\/a>
\u2713 Synthetic fertilizer
\u2713 Natural fertilizer (such as worm castings)
\u2713 Wetting agents (to help the peat moss absorb water)<\/p> Ingredient List<\/span><\/h2>
Why you need a soilless potting mix<\/span><\/h2>