Inert Growth Mediums

Vermiculite Growing Medium

Using inert growing mediums can provide plants with a solid foundation for development and help to regulate water and feeding.

Many gardeners prefer the use of inert growing medium when planting indoors. Growing mediums can be any number of materials, as long as they permit root access to water and air, are not degraded by moisture, do not contain pests or bacteria, and can be used by root systems for stability they should work. Systems that use inert mediums provide all the nutrient needs of plants with special solutions so the growth medium does not have to offer any nourishment, although some medium do. Some of the more popular mediums include vermiculite, perlite, rock wool, and coir although there are literally hundreds of materials that have been used.

Perlite

• one of the most popular inert mediums used in hydroponic gardening
• combination of granite, obsidian, pumice, and basalt rocks that have been fused during volcanic activity
• volcanic rock that is transformed into lightweight pebbles through a heating process
• can be used as the only growing medium for plans or mixed with soil to decrease soil density
• able to hold a significant amount of air and can be used for plants with root systems that need fresh air

Vermiculite

• natural mineral that is super heated until it expands into a lightweight, porous pebble material
• known to hold more water than air
• has a wicking characteristic that makes it suitable for transporting water in passive hydroponic irrigation systems
• so effective at drawing water they can sometimes flood root systems,  growers will often add perlite to balance out the mixture.

Rockwool

Rock wool

• one of the most popular growing mediums  for hydroponic gardens
• inert compound that is created by molten mineral substances
• fibrous material and very effective in transporting nutrient solution to roots
• effective in both drainage and recirculated systems.

Coir

• also known as coco peat
• material that remains after the fibers are removed from coconut shell
• totally organic material and does not undergo any manufacturing
• can be used by growers for many different plant types and indoor systems

Diahydro

• kind of rock that occurs naturally in the environment
• result of the fossilized remains of diatom
• particularly useful effective with species of plants that require high concentrations of silica
• can be up to 94% silica which is helpful for developing strong cell walls and structures

Clay Pellets

Clay pellets

• baked until they expand and become porous and able to transport water
• known as LECA, or Light Expanded Clay Aggregate
• baked clay pellets are useful for growers who need to have clean medium
• does not contain any nutrients or minerals
• completely inert, has a neutral pH value
• very strong so they can hold their shape and function for a long time
• must clean and sterilize pellets for reuse
• root growth from plants and enter and remain inside pellets.

Sand

• one of the cheapest and most readily available growing mediums
• can be difficult to work
• its heavy, has poor drainage ability, and needs to be thoroughly sterilized between use

Gravel

• used by many growers for their indoor planting medium
• aquarium gravel is often used because it is clean and an appropriate size a
• will often employ electric pumps and overhead watering systems to ensure a steady supply of nutrients
• drains very well, so well that if it is not continuously supplied with water roots can try out quickly

Brick shards

• known to be suitable growing medium for a number of different plants
• have similar characteristics to gravel from a gardening perspective
• can alter pH readings and must be thoroughly cleaned before each use

Packing peanuts

• extremely cheap and easily available material for growing
• light weight and provide excellent drainage
• may be health concerns
• compounds used in production packing peanuts may breakdown in water or supply plants with chemicals.

Wood fiber

• natural material that can be used as a growing medium
• very stable material that keeps its structure for a long time
• organic substance and so care must be taken that it is kept free of disease, pests, or fungus.

No matter the growing medium used it is important that it provides adequate nutrient delivery and drainage for whatever plants being cultivated. Mediums are often chosen specifically for their ability ti function with the irrigation method being used. It is a vital that all mediums are thoroughly cleaned and sterilized before planting. Any pests or bacteria that is present on a medium will almost certainly infect the plants being grown.