Dry Stall is supposed to be large. Little smaller than a pea. It is made for horse stalls. It would not be useful if it created dust when the horses walked on it. Joe On Jul 2, 2013, at 4:46 PM, Rodger Whitlock <totototo@telus.net> wrote: > On 2 Jul 2013, at 15:33, Ina Crossley wrote: > >> I am using pumice in my mixes, but only recently. I bought the 7mm one >> which seems to have a lot of dust and small stuff in it. Does it still >> do it's job of drainage with all the small stuff filling any gaps. > > If you intend to pot up a plant in nothing but pumice, be sure to wash it. I > have found that otherwise, the fines are washed down to the drainhole, pile up > against the piece of fly screening I customarily put over the hole, and block > drainage. > > Pumice by itself is a very good potting medium for certain plants. I use it for > Weldenia candida (which happens to grow natively near the tops of Central > American volcanoes, according to the literature), and a few honest-to-God high > alpines. > > Pumice is actually quite nutritious in a limited sense, containing a lot of > potassium. > > You are justified in your unhappiness with this supposedly-washed pumice you've > been sold. Even when it's going into a potting mix, I wash it first over a It's > shocking how much fine material comes out. > > > -- > Rodger Whitlock > Victoria, British Columbia, Canada > Z. 7-8, cool Mediterranean climate > _______________________________________________ > pbs mailing list > pbs@lists.ibiblio.org > http://pacificbulbsociety.org/list.php > http://pacificbulbsociety.org/pbswiki/