Re: "Is there a thread that will tell me exactly how much to mix of each and how to screen etc?" I'm sure there are many others that are just as good, but I happened to have this one bookmarked: http://forums2.gardenweb.com/forums/load/contain/msg031028425011.html It's a 1:1:1 mix, or equal parts by volume, of the granite, Turface, and bark. As for screening, that's covered more in the thread, but I believe you're aiming for a particle size of between 1/4, and ideally 1/8 inch, but 1/16 is acceptable. I was never able to find a 1/8 screen, and screened everything over an aluminum insect screen (1/16) without any real ill effects besides needing to add a wick in my largest pots. Here's what my last batch ended up looking like: That said the ratio not an exact formula that you have to follow. Example: I'm trying a mix of 1 part bark, 1 part granite, 2 parts Turface for more water retention in my potted hydrangeas. Once you get the hang of the mix you can try to adjust it to suit your needs, but honestly out of almost 30 different kinds of plants and trees I grow in containers - the hydrangeas were the only ones I felt compelled to mess with the ratio, everything else seems to love the mix. Though one of my orchids is being finicky in it... Here is a link that might be useful: Al's Gritty Mix -- A Learning Experinece

Yes you can, and in the short run 5-1-1 in may actually perfom better than the Gritty mix. But it will wear out quicker (break down) than the gritty mix. I tend to think of annuals going in the 5-1-1 mix, and perinnials in gritty mix. If you are going to be up-potting in a couple of years go with what you have. Either are a better choice than most anything you can find in most garden centers. Gritty mix makes future repots a dream, tip the pot over and you have bare roots.. Grading the pine bark is not fun, I hate it! A major concept of the gritty mix is based on particle size, larger particles have less surface area (by volume) and thus less water retention. 1/4 to 1/8 inch seems to be the optimal size, although due the screening process of pine bark and the thin strips I will let most 1/2 and under get in the mix (under 1/8 is not good either). If you are looking for Turface MVP check a local irrigation supply house, the stuff was designed for baseball diamonds so look in that direction. The dust is not good for the mix (particle size) The gran-i-grit is intended for chickens to help them digest grains. There are many other products other than gran-i-grit that will perform just as well. Look to a local farm supply house for the rock. Rock dust is not good for the mix (particle size) Gypsum is available at the big box home improvements stores. Gritty does dry out quicker than potting soil so you do need to water a bit more often. It is extremely difficult to overwater with gritty mix, that includes mother nature overwatering. Root rot is probably the number one killer of potted plants. After water, air is the most important thing you can give roots (most plants), more important than fertilizer. Gritty mix excels at this without drying out the root system. Gritty mix is heavy stuff, an advantage of heavy is the pot is less likely to tip from heavy winds. Al is a smart guy, it is such a simple concept.

I wanted to agree with everyone, but if the grit wasn't the appropriate size (grower size is great) I couldn't be sure the bark size was appropriate. For instance, if the grit was turkey size, the grit and both size gradients of bark would be too large. You're golden. I actually didn't notice there was DE and grit side by side, which would surely strengthen the case for the size being appropriate, base solely on the picture, so everyone else's eye was sharper than mine today. ;-) Al

@Nil13 made reference to the Whitcomb 311 mix, which is an earlier historical attempt to create a more coarse potting soil for container plants. I think it is extremely helpful to read a document written by Carl Whitcomb that explains how he came on this formula by accident. Essentially what happened is he accidentally left nine test pots under a bench and everyone forgot they were there. They had successfully nearly killed all of their test plants by watering in a normal potting soil mix and the unwatered plants started to do very well. What I have started to realize is that any plant can do well in many different soil mixes, if you are able to carefully control the watering. This explains why so many people on this forum claim gritty mix is not as good for their succulents as their (fill in some random horrible soil with lots of small particles) mix. Inevitably those people are growing their plants indoors. They have enormous experience with their plant type and they know exactly when to water the plant. So that is the case of a very skilled gardener compensating for a very bad soil. What gritty mix does for me is let me grow succulents outside in very abusive weather conditions, without the plant dying. A plant can get a week of rain and it will still drain well. During Summer, gritty mix will tolerate a bit of overwatering, although you still really need to pay attention to not overwatering. Whether you make your 511 mix with perlite/peat, or with two parts Turface, or with lava and pumice, is probably in the big picture not going to be the deciding factor in whether your plants grow well or not. Success can be add with any of those mixes because the size of the particles allows the roots to breathe and prevents capillary action of water from bring the perched water table to the top of the pot and drowning the roots. Fine-tuning how you make 511 is a question of matching the plant type to the moisture retention of the soil and to the watering habit and climate exposure. Any 511 variant is going to do better than almost any commercial potting soil because of the larger particles used in the majority of the mix.