Beginner Gardening: Good Growing Practices - an Overview for Beginners, 1 by tapla

tapla wrote:
For plants that need repotting (as opposed to potting up) EVERY year to perform at their best (like Colocasia), I use a mix of 5 parts pine bark fines, one part of peat, and 1 part perlite. Keep in mind that even plants that do well in boggy conditions where they naturally occur, seldom tolerate the same boggy conditions in a container. A stellar example of that is the peace lily. It often grows in standing water at stream side, but quickly collapses in containers when soils are too wet - as will Colocasia.

Plants love lots of oxygen in the root zone; you can say the more the better, within reason; in fact, it's as important to have enough air in the root zone as it is to have enough water. Ideally, you would have a soil that holds a very favorable mixture of water and air. This is most efficiently accomplished by using larger particles that hold water inside the particles - like pine bark. To visualize, think of a jar of marbles as a soil magnified, but imagine the marbles as being porous. In your mind's eye, can you see all the wonderful air space between the particles to make roots happy? ..... and the water IN the absorbent marbles being utilized as the plant goes about its business? Soils that are predominantly pine bark or other suitable particles employ the same principle.

The soil I use for Colocasia is in the middle. At 3, 6, and 9 you can see suitable pine bark fines from 3 different suppliers. The fir bark at the top comes prescreened & is what I use for the gritty mix.

Al