Diana brings up a good point. I've found that the horticultural grade perlite avaliable in small packages in "big box" stores, etc. contains a large amount of fine material. I once sifted (outdoors!) about a quart (liter) of dry perlite through 1/8 inch (about 3 mm) mesh and found that the fine material made up about 1/3 to 1/2 of the total volume. It may be that this fine material is retaining most of the water and causing problems. The coarse grade of perlite is much used in orchid circles where it is often referred to as "sponge rock." Eugene Zielinski Rapid City, SD USA > [Original Message] > From: Diana Chapman > To: Pacific Bulb Society > Date: 10/24/2012 8:46:53 AM > Subject: Re: [pbs] Water retained by various soil ingredients > > As Leo pointed out, there are other kinds of perlite. I couldn't do > without perlite, and use huge quantities of it, since I have hundreds of > pots, some very large, and moving and carrying them is a daily task. I > started using the better quality perlite some time ago. It has been > specially heat treated, and comes in three grades, the medium one is > about bean sized, and it has no dust or fines associated with it.