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

tapla wrote:
Exactly. You're shooting for a coarse mix that holds lots of air between the large particles, with most of the water being held within the porous particles. Water retention is closely linked to particle size. The reason most commercially produced and bagged soils are so difficult to grow in over the long term, is because the particles that make up the soil are so small that they hold water between the particles instead of air. All container growers will benefit significantly if they remain aware of how important ample volumes of air are to root function and plant health. Most of the problems container growers come to these forums with, seeking resolution, are the result of the heavy soils they are growing in. Even the disease and insect-related problems are most often the result of the plant's inability to produce the bio-compounds that form the plant's natural defenses against these pathogens; this, because of poor vitality and a sluggish metabolism resultant of impaired root function. Healthy roots are essential to healthy plants - no healthy roots = no healthy plants.

Al