When it comes to root health, pots with gas permeable walls carry the day. Terra cotta clay pots are better than plastic or vitrified clay pots and fabric pots are better than terra cotta clay. The reason is greater gas exchange through container walls and the fact that an increase in gas exchange comes with an increase in evaporative water loss, which can be a lifesaver when using water retentive media. There will still be a PWT in these pots, and for any given medium it will the same ht in a pot with rigid sides as in the fabric or air pots at container capacity. Container capacity is a measure of how much water the grow medium in a pot or container holds at the moment it has stopped draining after having been watered to the point of complete saturation. The ht of the PWT and how long it affects root function is usually key/critical in determining what opportunity a plant will have to realize as much of its genetic potential as possible (within the limiting effects of other cultural influences). The factor that most affects the ht of a PWT is the size of the particles from which the medium is made. So, reducing the duration of PWTs limitations increases the opportunity for plants to realize a greater measure of their genetic potential. But wait! There's a more important consideration. If you place your fabric containers directly on the ground/soil, from the perspective of hydrology it changes the fabric container to a raised bed; this, because water is free to move through the fabric between the grow medium and the earth, with the earth acting as a giant wick. This means, because of the increase in the force of adhesion in the mineral soil beneath the pot (due to a mineral soils much larger o/a surface area on a per volume basis), water in the soil will be pulled downward with enough source to overcome the capillarity holding it perched in the container. As long as you don't place the fabric container on coarse sand, peastone, or other large particles, the earth will likely pull all perched water from most media one is likely to use in a container. I've mentioned this and the fact that healing in your pots situating them directly on top of soil turns them into raised beds. the only caveat being it's essential that there is a 'soil bridge' so there is continuity of the soil column between the soil (earth) and the grow medium in the container, through the drain hole(s), so water doesn't have to jump an air gap to exit the container. This applies more to pots with rigid walls and is not a factor when discussing fabric containers. Al

Yes, I stated that I'm not worried about the aluminum, all the same I won't use aluminum sulfate either. Although it may be safe, I worry about toxic levels. Just because lead is in all soils doesn't mean it's a good idea to add more. Same with aluminum. And if you mix turface without a mask, you will be exposed to it. As far as water absorption Axis noted that turface holds 95% of it's weight in water. Pumice only holds 15% and DE holds 142% Try diatomaceous earth in your tests. Optisorb is about the largest size available to home gardeners. Axis makes an excellent size, but is for commercial use only. Numerous studies document it's use as superior to most other amendments. Such as " Effects of diatomite on soil consistency limits and soil compactibility" by Ekrem Lutfi Aksakala, Ilker Anginb, , , and Taskin Oztasa Or "Effects of diatomite on soil physical properties" by the same authors. Also "Sustainable effects of diatomite on the growth criteria and phytochemical contents of Vicia faba plants." Mona M. Abdalla* Department of Botany, Faculty of Science, Ain Shams University, Cairo, Egypt. The Axis company also has great info on all amendments. As far as particle size, do a test. Fill a pot with sand, and one with gravel. Stick a pole in, and see which one gives more resistance. It seems to me gravel would. But I might be wrong? I don't know physics well enough to figure it out on paper. Ah and pumice is further dashed to the ground and called a fake, not a single user rises to defend. Well we can agree to disagree, my day job is a laboratory researcher,or was, I'm retired. If turface has various pore sizes then it is not very well made. Thanks for pointing that out. So you do not believe the manufacturer? Controlling pore size in fired clays is often accomplished with the use of polymers such as Polyethylene glycol. This process is extremely important to control how well purifiers work, or how well they hold up with the addition of salts. You are incorrect about the pore size. Yes pore sizes differs, but that process is used to make different products, and is very controlled. Turface is meant to have small pores size or it would ineffective in it's intended use. The porosity of fired clays is extremely important to have a consistent product such as fired brick used to built houses. Varying pore sizes will compromise the strength of the brick. Selling a product and manufacturing one are very different things. The pore size I reported is for calcinated clay. Range of pore sizes is from .1 -.01 microns. Median is .045 . Plants need a .2 micron minimum pore size to utilize. This info is from a study by Andreas Kalytta-Mewes, Kathrin Mattern, and Armin Reller University of Augsburg, Chair of Solid Body Chemistry Georg Armbruster Soil Laboratory. The pore analysis in the study was conducted by Quantachrome,Bavarian Institute of Applied Environmental Research and Applied Technology. Of course it appears none of these sources trump Al. Who has not provided any data at all to back his claims. Please prove to me that pore size is bigger, thinking Al is right because you sell clay products is not proof. After saying all this will turface work? Yes, it will. Works pretty good! Is it ideal? No, it's not, but what is? It's still worth trying for sure. It didn't work for me, but that means nothing. it has worked well for others. It would be nice if it allowed easier access to stored water, but it does store water, and air, and it lasts a long time, maybe 20 years. That's decent. It's a decent product, or appears to be. It would not be on the market if it didn't work. I know it's not meant for potted plants, but it is meant for grass. DE seems a better product, it has it's own problems. it is marketed though for plants more than ball fields, although it is marketed for that too. It's marketed for large commercial gardens. I use it in my garden. I use turface too for my grass, works well. Just not that well in pots for me. All i said that it didn't work for me. Sorry blame me, it's what you usually do when the mixes fail, you blame the poster. Many have said DE doesn't work for them. I actually believe them. All gardening is local. This post was edited by Drew51 on Mon, Dec 29, 14 at 15:33

Mike, Hey sounds like you have a great handle on both the 5-1-1 and gritty mixes! It took me a long time to find all the ingredients and figure out the fertilizer side of things, but once you do some reading of this thread and the previous eight threads it does make sense. Al was most generous with his time, both on and off-list, and answered many of my "newbie" questions. I'm sure your plants should respond much better using these soil mixes next season. My trees are showing huge root growth this season in the gritty mix. Granted, hunting down the ingredients, sifting fines, and mixing the soil it is a bit more work than just buying a bag of MG potting soil, but I have no doubt that in general plants grow better in the 5-1-1 and grit mixes with proper fertilization, watering, drainage and air movemnet through the root zone. The peat in the MG soil acts like a sponge and retains far too much water for far too long, preventing air from getting to the roots and keeping the roots soggy. I agree that typically the big box stores are not very helpful when it comes to finding the right ingredients for the soil mixes. Granted, a few list members have found the right size of pine bark, turface or even silica sand at a HD or Wal-Mart but typically in my area you have to go to local hardware stores, feed stores, etc. to find the ingredients. In my experience, if you go to HD or Lowe's and ask for turface no one has any idea what you are talking about. Sounds like you've already found some great sources for your materials! Good luck next season and be sure to keep us posted on how your plants do in the new mixes. Thanks Dave

I also have found coco coir to be excellent for seed germination. Coir is going to be superior peat for this for the same reason a paper towel is. It actually allows the seed to stay consistently moist. Peat dries out faster and doesn't have a reliable pH. You also don't have to worry about a bunch of sticks with coco. No nutes necessary for germination. The seed has its own food. Problem is, you have to transplant pretty soon or use liquid fertilizer if you use a medium without nutrients. I make soil blocks with a coco coir/vermicast/sifted compost mix so I don't have to worry about a quick transplant. Coco also won't mold or grow moss and algae on it like peat moss does. At least not until you put nutrients on it. It's just you adding the nutes instead of a pump. There is a very good reason peat isn't used for hydroponics but coco is. Coco is more stable, nearly all brands desalinate as they know the hydro industry is their number 1 customer - so normally no worries concerning salt, and it it's great for aeration because it doesn't break down as fast as peat moss. In fact, I sterilize, desalinate, and reuse the coco for my hydro plants. It lasts at least 3 growing cycles of tomatoes and many more for lettuce (shorter cycles is why). For anyone thinking, "But I don't do hydro," keep in mind that potted plants that require liquid fertilizer is hydro. It's just you adding the nutes instead of a pump. I hold no illusion that coco is more environmentally friendly. I did, because I fell for the media hype. But the reality is otherwise and I now definitely recognize this.