Thanks for the great response!
Although many bagged mixes growers are using consist of mostly of peat, you are right any loam should provide Si.
How much is optimal is debatable beyond my level of experience!
I'm assuming by your postings you have some prior knowledge of his grow and happen to know if he's growing soilless or not. I however do not.
As for going completely without Si in a hydro set up, I cannot speak to, but I'd love to know more about how it doesn't benefit the plant.
Just because it does not show a typical deficiency without it, does not mean it has no benefits and I can see you agree with me there.
Once we have that established, I think the only question is how much is optimal and is it already being provided in the medium.
No, not really. I just chimed in on the use of Si....
Here comes the usable knowledge I have. Shortened and said in easy to understand terms
Factors and things to consider on Si and it's use in Cannabis growing.
Si plays a major role in Monocot plant developement (grass's and grain's).
Monocots are also "accumulators" of Si.
There are 3 levels plant designations, as to Si levels in the plant.
Accumulators
Intermediate
Non - Accumulator
Cannabis is a Dicot or broad leaf plant. It falls into the low end of Intermediate or high end of non accumulator. Depends on your view and how you classify the Si in the plant (Growing, or dry % by volume)
For the sake of this post. We will use the dry concentrations as baseline.
So a Rice plant dry will have around 10 - 11 % Si by volume. While Cannabis is more around 2.5 to 3% and that's a variable by strain thing.
Getting enough Si is rather easy... The water you use, if not RO, will have an Si amount in it. Even dust has an Si value
The higher quality Hydro lines will have amounts in it. Off the top of my head,,,,Hesi, Cyco, The now defunct Flora Nova line.....Have some in their mix...
Getting too much can be easy too......Not exactly sure of amounts but, I know from school that supplementing it more then 1 time a week at over 200 ppm in media's with limited availability is a no-no.
In hydro applications you should have no more then around 35-45 ppm of Si value in the res. for plants (veggies) of the same Si % value in the plant. Over this will cause Si related tox problems pretty fast.
So what did we learn here?
#1: Supplementing Si in limited availability media's. Should be done once (1) a week and to do that for cannabis at about 75 - 100 ppm value per supplement.
#2: In hydro supplementing of Si. Ebb systems, DWC or constant contact (with the roots) systems, should have a res value of (to be safe but deliver good value) 40 ppm.
A: This should be halved in any RDWC system to start. Adjust as you feel safe but do not jump right in at 40%.
The actual benefit's of Si use in cannabis. Relate directly to the actual benefits of Si to the plants.
These include..
Limiting P in P over use....Not much but, it does have this effect.
Limiting the possibility of metal tox situations by limiting or some say the "balancing" of Micro uptake.
Strengthening of cellular walls. The real benefit of this is somewhat dubious. While it
does help with the plant resisting invasions from insects and Molds....The effect is recorded in experiments to last out over low Si content plants.. An increase in time before the plant is infected.
This increase in time to infection is about 5 - 18 days in "like" Si concentration plants.
So, you still GET that infestation or infection. It just takes longer to happen!
As far as any added benefit from thicker stems and such....Not really! You must remember that the whole plant is getting that same increase.
This increases ash when smoked by increased cellulose amounts...Not a win.
A few extra points to ponder..
Si accumulates as the plant grows in new growth zones only! It will not translocate!
Si use in small amounts. Can be best done early in a seedlings/clones life. This is the best time for any Si use, if you "need" it.
If you water it in (drench) and don't do any leeching in a soil-less media grow. The use of Si should be done on a reducing, sliding scale...."It will build up." If you water to runoff....Weekly should be your amount of supplementation...
These are the things remembered from several class's in college and put in a non-technical explanation....
Welcome to Silica use 101 here....
Note: Online postings of the wonders of Si use are slanted to NON cannabis plants. Many cannabis related answers on differing sites are, well, formulated by guessing the answers from the needs of other plants....Speculation at work..
Yet, speculation by needs of other broad leaf plants, with the same basic Si content as cannabis. Is the starting point for my answers on how much to use and how often..
Always remember what I said above (post above this) about how to mix! Very important!
Good luck and don't over do it!
Doc
Thx
