Specialty Gardening: Second Generation Potting Soil, 1 by tapla

tapla wrote:
I was just having a similar conversation on another forum. The lava rock is somewhere in between Turface & granite, so it reduces the ease of adjustability. Here's how the other conversation went:

He: "..... you mention that the scoria (lava rock) and haydite (expanded shale) do not contrast nearly as much as Turface and crushed granite. -- is that a bad thing? will less diversity compromise a soil mix?"


Me: Not really. It just makes it so much easier to adjust the water retention of the soil if you have something like Turface or floor-dry with tremendous internal porosity and water retention to contrast with a product like crushed granite which has no internal porosity and very little water retention. E.g., a soil with
3 bark
4 Turface
2 granite
would hold much more water than
3 bark
4 granite
2 Turface
When there is little contrast between the ingredients, it makes for more guesswork, but I suppose that if you get used to what you're using, adding/subtracting ingredients to achieve your desired level of water retention will become second nature.

In almost every case, the (relatively) small plants we keep in containers don't need the big pipes & anchors. The finer roots are adequate to anchor container plants in the soil, and since the feeder roots are bifurcations of larger roots, the larger roots will ALWAYS be adequate for any hydraulic transport furnished by their smaller workhorse counterparts. A tree in the ground that is 20' tall might need several 6-10" thick roots to anchor it, but a plant with 1/1,000 the mass needs only roots large enough that they won't break in a breeze (1/8-1/4" for a sizable tree). Tiny roots rock! ;o)

Take care - good growing. ;o)



Al