I repotted 5 plants into my attempt of a gritty mix. A beech and four firs, all plants that prefer sharp drainage. Its been 4-5 weeks and sadly the beech and a concolor fir is already dying and I now fear I will lose the other three as well. I have some 25-30 mostly conifers in the 5-1-1 mix and they are all doing great and I have not lost any. So I am puzzled if I am over watering or under watering my attempt at the gritty mix, and if my plant casualties are due to root rot or roots drying out. I have been using a wooden dowel to check but since the water fairly quickly drains to the bottom I have for the most part been watering the pots every other day.

Is the Napa floor a poor substitute for Turface?

If I have some perched water at bottom of the container with my gritty mix is that an indication that I have made a misstep when making the mix?

I have been tilting the pots to drain the excess water so I would be surprised if the plants demise is caused by root rot. I trimmed the roots some when repotting so the majority of the root mass is in the top 2/3 of the container anyway.

Any advice would be greatly appreciated.

I have seen reports of 2 different variations on the Napa #8822, only one of which is suitable for the mix. I can't find the original thread but it was something to do with "amorphous" vs "calcined" DE iirc. Also, here Al says the floor dry retains more water than turface, so that could be the reason: https://www.houzz.com/discussions/1388596/using-napa-floor-dry-in-the-gritty-mix

On second thought, if the particle size is right the water retention shouldn't matter in terms of the PWT -- water stored inside the particles wouldn't come out from tilting. If it's not calcined DE though that could be an issue.

One more thought on rereading: you mentioned the floor dry size was 1/12" on the low end, which is a bit small. That would allow some perched water, but imo not as much as you seem to have. I'll let someone else weigh in on that since I'm no expert.

Thank you for the info and suggestions!

I not aware of different variations of Napa #8822. The bag does not list any information regarding ingredients other that it being diatomaceous earth absorbent. NAPA list three different floor dry products but only one #8822. Next time I'll try harder to source Turface.

Its was my understanding the Turface/floor dry component should be 0.08 - .125 ie 1/12" - 1/8" but perhaps a large percentage of my sifted material was at the low end of that range.

I realize why I couldn't find the thread, I was looking on the wrong website: https://www.reddit.com/r/houseplants/comments/bgmvme/comment/eta7yfe

Actually now that I look for it, I can't remember seeing an exact number for the Turface size, I guess I was just assuming it should be 1/8-1/4" like everything else. Most of Al's posts don't list it, where did you see 0.08?

I use Bonsai Jack soil and they source a custom 1/4" Turface product, so I haven't dealt with the sifting myself. All I know is 1/10" is the lower limit to fully eliminate perched water.

Could you post some pictures of your mix?

Thank you. After your mention I did find some of post on other websites about NAPA floor dry product labeled "calcined diatomaceous earth" vs "amorphous diatomaceous earth". I had a spare bag left of the NAPA product and there is no such information their current packaging. It does say kiln-fired but I don't know if thats any indication of it being calcined.

I took a couple of pictures of my mix. It just rained so it's wet. I find that the bark likes to clump together in one area. The other three firs I have in the mix shows no sign of decline as of now and seems to be thriving. In one container I place a cotton string at the bottom so that one pot seems to wick the bit of water that collect at the bottom.

Sorry photos didn't upload