Specialty Gardening: Dealing with Water-Retentive Soils , 1 by tapla

tapla wrote:
* "I'm still surprised that tiny seedlings with tiny roots would be happy with coarse particles, straight from the bag or even screened, if this still refers to sizes no smaller than 1/16" (1.6 mm) and averaging just under 1/8" (3 mm)? What do you use for a screen?"

Seedlings/many cuttings will grow like crazzy in a jar or plastic bag, resting on top of nothing more than a damp paper towel - no soil at all - just high humidity. I wouldn't complain if the particles were 1/16 - 3/16, but the PWT disappears as particle size approaches 1/10", so 3/32 would be the ideal lower limit.

See what I made for screens below.



* "Do you have to water seedlings in this more often than once per day, once the humidity cover comes off?"

No - even materials with no internal porosity (crushed granite, perlite) usually hold enough moisture to co several days w/o watering. It depends on things like air movement, temperature, r-humidity levels, size of the seedling(s) in the container, what the container is made from (gas permeable?) ..... You can always mix ingredients - like Turface & granite or perlite to get the water retention you want.

Al