(I hate they have a Pro by my name. Yes, I work in horticulture for many years mostly with annuals, trees and shrubs. Still lots to learn, about a lot.)

Sorry, for the length. Thanks to all that read it.

Pictures are the bottom.

Hello All,

I am looking for a few theories. I have my own, but I'm not sure I buy it.

I am trying to create a medium that even people buying their first plant will have success. Lots of trial and error. I thought I was real close. I thought a few more tweaks and I've got something nice. I have been reading lots of peoples comments. Paying most attention to professional growers that cared. I am frustrated that growers use what works best for them, whether it's cheaper or easier. Only caring waht the plant looks good at time of sale. I am also frustrated that the only choices for people are CSS that are either too dense or a good peat potting soil with extra perlite. Neither is ideal.

Ingredients;

• Pumice (2 sizes 1/4-3/8 and fine),
• black lava rock (Lava Grow),
• bark (new & some partially decomposed)
• perlite,
• Bacillus thuringiensis subsp. israelensis (BTI),
• Bacillus subtilis QST 713 (Natria - Expired) (New testing shows it can be used as soil drench to kill multiple root rot pathogens)
• MG CR 12-4-8, &
• multiple strain mycorrhizal fungi (not very much, I only had a little bit left).

Some plants by day two I notice the Crassula muscosa were looking worse than just shock. I find these guys are the best indicators when something is wrong. The plant came out with nothing below the soil but black plant and roots. The Echeveria in the picture, previously had a fuzzy brown stem with some nice new roots. When I scratched away the black skin on the stem, it is green below. Same as some Aeoniums also tested, both rooted and unrooted.

When planting I notice more finer particles than I had intended, but I figured it's a test, so test it. The plants I had used larger particles, such as Haworthia and Ledebouria violacea (Scilla violacea ) were uneffected. The both had larger roots. When I took the Ledebouria out of it's previous pot, it had the most magnificent roots, bright white with tons of small filaments. It was the last thing I planted. So, when I noticed the problem, I quickly removed it from the new soil.

Some of the pumice, bark and perlite had been in a previous mix with compost and very fine coir. I had sterilized in oven, sifted the compost and coir out and washed it. Obviously some of the compost was still embedded in those particles. Which I had thought was a good thing.

I have used all the ingredients before. Never having any problems. I may not have washed all the lava, but I had never in the past. The Echerveria had recently grown roots and recently planted in a mix that included lost of lava rock, before I moved it into the new soil.

I've never seen roots rot this fast.

I had sifted the items through two different sifters, separating the larger pieces from the small. I have since remembered I stopped using the smaller pumice in the past because it compacted.

I used the BTI, because the previous soil with compost gave me a big fungus gnat problem within in one week. I have pretty much eliminated them, with drying the plants (soil) out, then watering with BTI. I did not want to risk the few i had left still flying around getting into the new soil.

When sifting the mix, I used one sifter to get out the larger particles for plants like Agave and some Haworthia. Then I used a very fine sifter to get our the silted.

I have started over. I still sifted out the larger particles. The next sifter is not as fine as the previous, something in between, removing the grit.

All the new mix is straight out of the bag.

• Pumice that is 1/4-3/8 only. Eliminating finer.
• Black Lava Rock (Lava Grow) (brand new bag)
• Bark (fresh-not decomposing - new bag) I need to find some smaller sizes. For now I am breaking some up.
• Perlite (Increased the amount) (some smaller pieces were added by mistake, but not as small as particles sifted out, shown in a pictures below.
• BTI,
• MG CR 12-4-8
• Bought new bag of single strain mycorrhizal fungi today (I will add now - reapply in two weeks)
• Bought new jug of Rapsody ASO will add to first watering.

The first four, sifted (both screens twice) & washed twice.

I planted a couple things for now ( I currently have quite a few plants bare root waiting to see how this goes)

Any theories before I get too far. All I can come up with is super speed rot and possibly some lava dust smothering the roots.

Some of the plants only had short stems, not deep enough to be compacted or drowning.

I have no pesticide or herbicides, except to the bio-fungicides mentioned.

• Roots look worse in real life. Fall apart then touched

• Original killer medium with dime and quarter

• New medium with larger particles

• New medium with smaller particles with some larger pieces to break up consistency

• Comparison. Don't look it, but these are dimes.

1. New larger
2. New smaller
3. Small particles from killer medium. no longer in new mix

Thank you for time. It is much appreciated.