Years ago, at the NARGS winter study weekend in Framingham Massachusetts, Bill Cullina did a marvelous lecture on this, complete with all sorts of slides showing exactly what the water table was doing when there were coarse particles at the bottom and fines towards the top (he built soil profiles between sheets of Plexiglas). Water fills the smallest pore spaces first, and only when those are filled does it move into the larger ones. Thus putting coarse material at the bottom worsens drainage in the root zone, because it pushes the saturated zone higher. The only thing it does achieve is to make the container lighter (assuming you use cans, or chunks of Styrofoam, and not rocks). Ellen On Tue, Dec 3, 2013 at 2:59 PM, Mark Mazer <markemazer@gmail.com> wrote: > Capillary theory teaches that this simply leads to a "perched" water table > in the container. The USGA has done extensive research on the physics of > this on putting greens. > > "The layering of a finer textured and single grained soil material over a > coarser textured > media results in the formation of a zone of saturated soil above the > interface. This is > shown in the figure below. A necessary condition for this occurrence is a > distinct > interface between these two porous media as would occur in a USGA green > adhering to > the bridging criteria for the gravel. As we shall see later, this zone of > saturated soil is not > a true water table since it lacks a free-water surface (i.e. a depth within > the profile where > soil water suction equals zero). The soil is saturated nonetheless, because > the soil water > suctions that exist in this zone do not exceed the air-entry value for the > root zone. " > > It's time to put this practice to bed. > > > Mark Mazer > Hertford, North Carolina USDA 8a > > > On Tue, Dec 3, 2013 at 1:10 PM, Judy Glattstein <jgglatt@gmail.com> wrote: > > > Ina, when I used to teach container gardening classes we'd often be > > discussing those large wooden half whiskey barrel containers. My > > suggestion was to use aluminum soda containers, opening side down. One > > or even two layers, with second layer - if any - offset from the lower > > layer. Then cover the cans with water permeable non-woven landscape > > fabric. Cut somewhat oversize, so that the fabric can be brought up > > against the side of the container for a few inches. > > > > Judy in sunny New Jersey where we've gone from night temperatures in the > > teens Fahrenheit into another heat wave. High 50s Fahrenheit predicted > > for today and the next two. Very peculiar weather this year. > > > > --- > > This email is free from viruses and malware because avast! Antivirus > > protection is active. > > http://www.avast.com/ > > > > _______________________________________________ > > pbs mailing list > > pbs@lists.ibiblio.org > > http://pacificbulbsociety.org/list.php > > http://pacificbulbsociety.org/pbswiki/ > > > _______________________________________________ > pbs mailing list > pbs@lists.ibiblio.org > http://pacificbulbsociety.org/list.php > http://pacificbulbsociety.org/pbswiki/ > -- Ellen Hornig 212 Grafton St Shrewsbury MA 01545 508-925-5147