Up to two thirds of your plants mass is in root mass. That means that if your root are unhappy your plant is going to be unhappy. So you need to make sure that the medium that you use will make a HUGE difference.
There are some very debates out there about the right craft soil, but you can mix your own if you want to.
You can buy pre mixed craft soil or you can mix your own. should you decide to mix your own, the basics are moisture holding, aeration and nutrients.
Start with the basics: Coir, Perlite, Vermiculite, and Compost
Coir is the outer husk of the coconut. It is by far the most ecological soil base because it is a farmed by-product of coconut production that has not been used economically. Until recently it was considered a waste product that accumulated in gigantic piles. Now indoor agriculture has created a use for it.
Perlite is made by heating volcanic hydrated obsidian glass. When it is heated to about 1500ºF, the water in the mineral evaporates and the glass expands into a porous lightweight state, much like what happens to popcorn. The expanded material does not absorb water but holds drops of water on its irregular surface. It keeps its structure in the mix to provide air spaces for water movement. It is chopped to pieces ranging from sand to pea size.
Vermiculite is made from silicate clay that is exfoliated using heat. The mineral naturally forms thin layers on top of each other that expand when heated, creating spaces between the layers that hold both water and air. It has a high cation-exchange capacity so it buffers acids well and helps keep the mix balanced. The mineral is soft and somewhat spongy when compressed. It has been used for growing for more than 50 years.
After mixing the Coir, Perlite, Vermiculite and compost in equal parts you can look at add the following
Activated charcoal – Helps buffer the mix by absorbing excess nutrients and chemicals and may have other benefits in keeping the mix adjusted. Charcoal is associated with healthy plants.
Alfalfa meal – Contains 2.5 percent Nitrogen (N) as well as 1 percent Phosphorous(P) and 1 percent Potassium(K). It also contains natural plant regulators such as triacontanol.
Bat guano 10-3-1 – Contains readily available N as well as small amounts of P and K. (I recommend using any combination of guanos including bat, seabird and cleaned poultry manure, to obtain high amounts of N and P.)
Coffee grounds – Contains 2.2 percent N as well as minor amounts of P, K, Magnesium (Mg) and Copper (Cu). The nutrients become available over a period of several months.
Kelp meal – Contains 3 percent N that releases gradually.
Mycorrhizae – These are the beneficial fungi that develop symbiotic relationships with the roots. They form a major portion of the rhizosphere community surrounding the roots.
Seabird guano—0-10-0 – This is a fast acting fertilizer that provides needed P to the soil. Bird and seabird guanos can be substituted with each other or with cleaned poultry manure (3-2-1) or insect frass to build up N-P-K values.