The way the particle size distribution of the gritty mix is supposed to work ensures good water retention, but with no or negligible volumes of perched water to affect root health/function. It's important that the small particles be removed to accomplish this lest they filter in between the large particles, rendering the soil supportive of perched water and eliminating one of the most significant advantages of the mix. Another significant advantage is the aeration inherent in a well-made gritty mix, which would also be a casualty of neglecting to ensure the sizes of the particles are appropriate. If you don't screen the particles, what you end up with is a mix that will perform like a lot of other mixes, and whose only essential variance from most other mixes would be its structural stability, a derivative of the fact that it has a 2/3 mineral component and the organic fraction (bark) breaks down very slowly. This is one of the less significant attributes of the soil though, because inevitably a plant needs repotting long before there would be even a hint there was a hint the soil had structurally degraded. In fact, with a 2/3 mineral fraction, even if the entire bark fraction was to break down or gas off, the soil would still be perfectly servicable. I don't think I've ever really listed the attributes of the gritty mix, so: A) No or very little perched water - the most important (root health) B) Excellent aeration (root health) C) Extremely forgiving and easy to grow in D) Adjustable for water retention E) Serviceable indefinitely - won't collapse (root health) F) Easy to make, once ingredients are located & you're set up to screen I love to see people using it, but I have to be honest. If you can't find the ingredients or suitable substitutes, or don't want to screen them, I don't think it's a good investment of time/effort to make something that will perform similar to a from the bag mix. More important than a recipe, is the concept. The gritty mix is simply the best way I've found to implement the concept described in the thread I'll link to below. I honestly feel that an understanding of the information in the thread represents the largest forward step a container gardener can take at any one time. Root health is often overlooked or given short shrift; but it's very important to realize that a healthy plant is impossible w/o a healthy root system. Roots are indeed the heart of the plant, so it pays to keep them happy. ;-) Best luck. Have fun at the party! Al Here is a link that might be useful: Learn about soils .....

Thank you, Butch. Lots of very good information here. I'll print this off and read it several times so I'll know what needs to happen in the soil for maximum root development. Don

Soil-less mediums work best for containers because they maintain viable structure and porosity. Soils and soil based mediums work in the ground because they become part of a much larger system. Once you take real soil out of that system....it no longer functions. Soil-less mediums (potting soils) provide anchorage, plenty of good air spaces (a requirement for germination, rooting, and normal plant development), and available water. Sand, silt, and clay are all of the soil components that work great FOR us in the garden, but AGAINST us in containers. Poking holes with a solid object compacts the soil around the holes. True aeration would remove columns of soil (like a core aerator for lawns). Best to incorporate something that provides nice pore spaces throughout the entire volume within the container. Seeds, also, need oxygen in order to progress properly, as well as moisture. That's why a soil-less medium IS ideal, if you are germinating seeds in containers. Most (so called) germination mixes are made of very finely milled peat moss, along with vermiculite and perlite. Those ingredients work to provide a steady supply of available moisture and oxygen. When I'm germinating seeds, I fill most of the seed flats with a very coarse textured potting medium, followed by a layer of the germination mix. After sowing the seed, I'll cover the seeds (if required) with more of the germination mix and use my misting nozzle to saturate the entire medium. The germinating mix insures that the seeds will have contact with the moisture providing peat. By the time the seedlings have begin to grow a little, their roots enter the highly porous medium.....then LOOK OUT! ;-) My potting mix is made of composted bark fines, peat moss, perlite, coarse granite grit (like for poultry), and Turface.

Potting soil and potting mix are probably the same thing. While superior to "garden soil" for use in a container, it is still not ideal in many ways. While it's a bit of read, this thread (http://forums2.gardenweb.com/discussions/2842847/container-soils-water-movement-and-retention-xxii?n=356) is very worthwhile and explains how containers have very different properties than the ground, and how media choices can turn some of these differences into advantages rather than limitations for your plants. Daniel