Lol just plain coco… a tiny chunk off a brick. $5
promix rooting hormone.
A really important factor is you only want to give enough light to keep them from flowering.
You don’t want them to spend nutrients and energy trying to photosynthesize. The goal is to allow them as little stress as possible so they can put the already stored energy into making roots.
Also photosynthesis is driven by light and they do not have root system to uptake needed nutrients and water to facilitate much photosynthesis.