Not sure what’s wrong

[az2000]

I found, years ago, that adding about 15-20% compost or composted manure makes a huge difference in growing with Promix. Previous grows without it were OK, but there was a definite difference in plant health and vigor. My theory is that the manure/compost adds micronutrients, major nutrients, and Iron. The wood ashes mainly add nutrients and a slight amount of buffering.

I never tried growing in Pro-Mix (by itself) with soil nutrients (like Jacks). The only way I used Pro-Mix by itself is with hydro nutrients, every 2 days, about 800-1000ppm each feeding. It worked very well. If I did that again, I'd reduce the strength 10-20%.

I don't understand how such a small amount of compost (or soil'ish Patio Plus, which I add) can make such a big difference. It's hard to believe it's just adding nutrients. It seems like such a small amount would be exhausted quickly if it were contributing *that* much (to the difference between with versus without). I have a feeling it's more about the rhizozone it creates. Something more hospitable to the microbes, more cooperative with the roots (their exudates, helping the microbes supply nutrients. More symbiotic relationship between two living things).

I still feed every watering (every 2-3 days when the plant has grown into the container). But, very low strength compared to when I fed hydro nutrients (without soil added to the soilless medium). About 200-250ppm not counting the water.

That's why this cactus mix seemed so odd. In my very light soil, I can do NPK ratio 1-1-1 all the way through (feeding relatively low strength). Suddenly, I have to feed 4-1-1.5 at twice the strength I normally do. (I haven't completely figured it out yet. But, it looks like it's going to be about like that.).

That's also why it seems odd that the small amount of "soil" I add to soilless Pro-Mix carries that kind of difference for so long (3 months). That's why I think it has something else to do with the rhizozone's health. A better environment for the roots to uptake nutrients.

Regarding the Cactus mix, I didn't consider there being perlite and vermiculite in it. Most of the cactus mix I have encountered was the junk that comes with a few cactus seeds and is 99% sand with a few pebbles thrown in. The stuff you are speaking of sounds much more forgiving.

There's no vermiculite in it. I'm thinking about adding vermiculite because the top inch becomes very dry. I noticed this already. But, it can be seen in the photos I took yesterday of the rootballs. (<<link) The top 1-1-1/2" is rootless. The cactus mix dries fast (and I like that), but there seems to be a lot of difference from top to bottom getting there. I'm thinking adding crushed perlite (crushed for uniform spread of the perlite between the sand/pumice particles) would allow for more even drying. And then, the vemiculite would help too by creating stores of moisture through the soil. (But, maybe just vermiculite would be good. I just think the large perlite pieces that it comes with don't help much. I think it would be better if they were in smaller pieces, occurring more frequently.).

I'll probably grow this again, and add a small amount of soil to see it makes the kind of big difference that I've seen with my soilless turned into soil (and, you've seen with yours).

 

[Jimster]

I don't understand how such a small amount of compost (or soil'ish Patio Plus, which I add) can make such a big difference. It's hard to believe it's just adding nutrients. It seems like such a small amount would be exhausted quickly if it were contributing *that* much (to the difference between with versus without). I have a feeling it's more about the rhizozone it creates. Something more hospitable to the microbes, more cooperative with the roots (their exudates, helping the microbes supply nutrients. More symbiotic relationship between two living things).

That's also why it seems odd that the small amount of "soil" I add to soilless Pro-Mix carries that kind of difference for so long (3 months). That's why I think it has something else to do with the rhizozone's health. A better environment for the roots to uptake nutrients.

When I started adding the compost/manure, I noticed a sizable difference in growth and overall health. I don't know if Promix used to use the Mycorr decades ago or not, but I always felt the difference was the iron and micro nutrients that the manure provided, although the manure would also introduce bacterial components that were missing from the raw Promix. Since there isn't much nutrients for bacteria to utilize in raw Promix, the added symbiotic fungus doesn't have a lot to work with. Adding manure or similar compounds provides food for bacteria (and the plants, eventually), which might account for the long term effect of the added stuff that you thought should have been used up.
I stand by using Promix, but it definatly works better with a few amendments in it. I've never tried using hydro nutes with it but I thought hydro nutrients were best used in a more acidic environment. With Promix, my Ph is between 6.5 and 7, using Jack's 20-20-20. Wouldn't a hydro nutrient draw the Ph down more, possibly fighting with the Promix buffering?

 

[az2000]

I've never tried using hydro nutes with it but I thought hydro nutrients were best used in a more acidic environment. With Promix, my Ph is between 6.5 and 7, using Jack's 20-20-20. Wouldn't a hydro nutrient draw the Ph down more, possibly fighting with the Promix buffering?

Lots of people use Pro-Mix soilless with hydro nutrients. Typically you ph the nutrient solution to 5.8-6.0 in veg. Or, 6.0-6.2 in flower. (Something like that, I've forgotten). The nutrients are more available like in hydro than in soil. It's something in between. I think it's customary to mix 1-2 Tablespoons dolomite into a gallon of Pro-Mix I think it was widely believed (experienced) that Pro-Mix's initial charge wasn't enough for the full grow.

I think that's a great way for a new grower to get started. There's no soil "mystery of life" to get in the way. Just you, god and the roots. The only downside: the new grower has to get into pH. Soilless will move more with the nutrient solution. More like hydro, needing the solution to be correct. (I think soil is better or new growers in that way, because it should be possible to grow without bothering with pH. Soil has more buffers, more "weight" to pull the nutrient solution to it as long as it's not over-strong. At least there's a chance of being able to grow without delving into pH. With soilless, it's mandatory.).

I think I'll add "soil" to the cactus mix and try another grow. If the improvement is anything like it was to my soilless Pro-Mix (and what you've experienced with your), it should be a good, light, fast-drying medium. Maybe the soil would make the medium dry more uniformly (no need for vermiculite, one of my other ideas.). If this cactus mix is like Pro-Mix (in terms of being relatively inert, not much nutrient value), it's amazing how much difference a mere "touch" of soil makes. I believe it's the rhizozone it's creating. The "dirty" quality it adds, encouraging microbial activity. It's hard to believe such a small amount of nutrients in that touch of soil would carry so much, for so long.

I was thinking about using one of the Espoma "tone" products. But, that stuff sounds like slow-release fertilizer, not "dirt." However, the Bio-Tone (<<link) has a large number of different beneficial bacteria. It looks impressive (even though I don't know what I'm looking at). I might use a small amount of that if/when I try to "soil" (verb) this cactus mix. I'll still use something like Patio Plus. But, a bit of that Bio-Tone might help get things started as a dirty medium.

 

[MIMedGrower]

When I started adding the compost/manure, I noticed a sizable difference in growth and overall health. I don't know if Promix used to use the Mycorr decades ago or not, but I always felt the difference was the iron and micro nutrients that the manure provided, although the manure would also introduce bacterial components that were missing from the raw Promix. Since there isn't much nutrients for bacteria to utilize in raw Promix, the added symbiotic fungus doesn't have a lot to work with. Adding manure or similar compounds provides food for bacteria (and the plants, eventually), which might account for the long term effect of the added stuff that you thought should have been used up.
I stand by using Promix, but it definatly works better with a few amendments in it. I've never tried using hydro nutes with it but I thought hydro nutrients were best used in a more acidic environment. With Promix, my Ph is between 6.5 and 7, using Jack's 20-20-20. Wouldn't a hydro nutrient draw the Ph down more, possibly fighting with the Promix buffering?

I think its because for young plants the nitrogen in compost/castings is easier to uptake and the addition of micronutrients like you said.

As they mature they have multiple sources of the nutes to draw from and the help from the good bacteria introduced.


To add. There is no difference between hydro and soil nutes except the ratio maybe and if they are organic or natural or chemical salt based. And the ratio is not as important in soil anyway.

I used botanicare kind with pro mix hp straight out of the bale and the addition of seaweed in the kind gave faster growth and better tasting buds than a base powder fertilizer did.

This supports your info about micro nutes as well. Seaweed is loaded and the micros are all available to the plant.