What makes a medium soilless or soil


@garrigan65 @latewood

A casual internet search tells me that the difference between a soilless medium and true soil is the presence of decomposed plant material “humus” in true soil. So if the medium is comprised of a good percentage of compost/humus/decomposed material (CHDM), in addition to other stuff like peat moss, perlite, etc., it’s a true soil. If coco or peat moss (or other non-CHDM substance) makes up the the good percentage of the medium, and there is minimal CHDM, then it is soilless. Is this is good rule of thumb? I find myself,a relatively new grower, commenting on other new grower soil media and giving direction to pH at 5.8 and 6.5, and want to make sure I am not leading people astray. If you have any insight, info, or convenient links, I’d appreciate it.


I know that soilless mediums wick away water whereas soil type mediums retain it a lot more.
What I was reading it sounds like you’re pretty spot on. I actually just grew with coco loco and I think if I was to grow again it would be soilless all the way, you get the best of both worlds really, just getting on a watering schedule, because you water so much, is extremely tedious. So if you could automate it on a drip system or something, it would make it so much easier.


You are pretty much correct. Basically there are the two media: coco/perlite and peat/perlite. Coco retains more water than peat and PH to hydro levels. Peat is airier and retains less water and PH to low soil values (around 6.3). Both have their advantages and disadvantages. I’ve grown in both and like them although favoring the peat based (Promix) right now. The one drawback is coco is half the price.

Peat doesn’t retain salts the way coco tends to and doesn’t need additional cal mag like coco. Less flushing (if you are into that haha).



This is a good explanation. PH soil and soil-less at 6.5. 5.8 is for Hydro.

Some folks will say to PH Coco coir just like hydro but this causes PH
issues throughout the grow. I like to tell growers to PH Coco or soiless
at 6.1-6.7, and I have great results.

Keep in mind that a soil less mix such as Pro Mix will become a soil a
year from now after a thorough natural decomposition.

Hope this helps. So; Basically, yes you are giving decent guidance.

Happy growing, lw


You would treat soilless as a hydro medium. This last grow I kept my PH at 5.8-6.0 and I had zero problem using coco loco. As long as you’re within a few points you shouldn’t have any problems either way. Your rootzone has the ability to naturally adjust PH to what it needs it to be.


Soil does not PH itself at all. You must amend the soil with the proper
additives in order for this to happen. Soil less medium is NOT!;
hydroponic medium unless you are using pure perlite or pure hydroton.


The soil doesnt, but the root zone can and does change the PH around it to allow for proper nutrient uptake.


The roots do not buffer the PH magically into the proper range. Some
minerals do though.


The rhizosphere does affect the PH around it.
“An accurate equation, solved numerically, also takes account of root hairs, mass flow and slow acid-base reaction in the soil. The pH at the root surface will often differ from the pH a few mm away by 1–2 units.”
" Plant roots can
modify the soil environment around them, so that the pH
at the root-soil interface (rhizosphere) differs from that
of bulk soil (Marschner et al., 1986; Darrah, 1993). The
rhizosphere pH as modified by the roots then determines
the availability of nutrients for the plants (Marschner,
1995; Hinsinger, 1998).
Rhizosphere pH changes mainly occur by the imbal-
ance of cation-anion uptake ratio in nutrient uptake
(Haynes, 1990 ; Marschner et al., 1986 ; N ye, 1981 ;
Riley and Barber, 1971). Plant roots release protons or
hydroxyl ions to neutralize the imbalance, resulting in
pH changes"
It’s not magic, its through interaction. Plants have been around hundreds of million if not billions of years, to think that there is no way for them to change the PH levels to what they need, and it’s all in the soil is pretty far fetched imo.