Soil is all in this world what a plant holds onto, and a well drained enriched soil is a single time investment for a plant to keep thriving till next re-potting. A right soil mix recipe can do a lot to plants that just providing nutrients, it keeps diseases at bay, deters pests and insects, provides structure and aerates the roots.
What is a potting mix?
A "potting mix" or a "potting medium" is a mixture in which a plant is grown. It may or may not contain soil and if it doesn't, then it is termed as soil-less potting mix. Although the recipe varies from one plant to the other depending on the thriving conditions but more or less the ingrediants remain the same. The basic components of a right potting mix are:
Soil or often called "Garden Soil" is the soil that is locally dug out from your outdoors. The kind of soil that is available around you influences the basic texture of the mix. For example, if the garden soil is too clayey we will try to enhance the texture by adding more coco-peat and some sand or pearlite as add ons for better drainage. Generally a basic soil mix of soil:peat:compost as 1:1:1 is made and then texture and othr attributes are checked. If required add ons are added to the mixture.
Peat or better say coco-peat is dry powdered compacted coconut husk which an excellent potting medium on its own. Sold as dry compacted lightweight bricks, coco-peat has excellent water retention properties; a 1 kg block of coco-peat can absorb up to 5 liters of water and provides right texture for draining excess water. Peat moss is dried decomposed sphagnum moss and serves quite the same purpose as coco-peat. We use coco-peat as it is easily available and to a stricter sense, "renewable".
Compost, or the living soil is all what is "Alive" in an otherwise barren land. I once read in the famous well written text by by Masanobu Fukuoka "one straw revolution" "These vegetables are a watery chemical concoction of nitrogen, phosphorous, and potash, with a little help from the seed. And that is just how they taste" Sadly, commercial agricultural practices have rendered the soil devoid of life. Compost is the life that soil needs. Make your own compost (Refer our Compost Guide) at home with some easy steps or you can buy as well. Although we strongly recommend home composting for its innumerable benefits.
Coarse sand improves drainage and adds weight to potting mixes. Mixes formulated for cacti and other succulents tend to have a higher percentage of coarse sand in their composition to ensure adequate drainage. The drainage capacity of sand is further enhanced by adding vermiculite or pearlite as an addon. But in case we don't want to go that far, a good amount of sand will definitely do it.
We generally mix the above three ingredients i.e Soil& compost mixture, coco-peat and sand in equal proportions and check soil texture and pH. This is the basic composition that I always make for potting. Variation for different plants can be achieved by adding following Addons.
Charcoal( Nutrient retention and Air purification)
Neemcake (Pest/disease control)
Lime (Balances acidic pH)
Pearlite(drainage and timed nutrient and moisture release)
The quantity and type of Addon varies from plant to plant. For example succulents need better drainage , lesser nutrients and slightly acidic pH. So we add some pearlite or vermiculite( a hand full to a 15 litre bucket) to our basic composition. Measure the pH and add lime to neutralize if pH(around 6) is too acidic.