Shcrews 15-20lbs plants in 1000 gallon soil mounds are some of the largest/highest yielding individual trees/plants ive seen, but that style of growing does not work for everybody, lol.
(Im referencing fabric pots during this explanation because there are alot of threads easily found by searching, discussing the yields in them and it gives standard to the dimensions and soil usage. What i explain here can easily be verified by google searching the topics i discuss here and reading threads from the various grow forums going back close to 20 years. I have done a considerable amount of research in reference to digging different dimension holes outdoors and yields as well, it also correlates closely with my findings.
Shcrews as an example:
15lbs = 240 oz ÷ 1000 gallons of soil = 0.24 oz per gallon of soil.
20 lbs = 320 oz ÷ 1000 gallons of soil = 0.32 oz per gallon of soil.
In my experience/research ive settled on 1 oz per gallon of soil as a reasonable average up to a 65 gallon fabric pot 32" wide by 18" tall. From sizes bigger ive noticed rapidly diminishing oz per gallon of soil yield returns.
Its not uncommon for growers to claim yeilding 4lbs out of a 65 gallon fabric pot.
4lbs = 64 oz ÷ 65 gallon = 0.98 oz per gallon
I have also found quite a few claims over 1 oz per gallon of soil, highest claim was "over 7lbs Blue Dream" from a 65 gallon fabric pot watered everyday.
5lbs = 80 oz ÷ 65 gallon = 1.23 oz per gallon
7lbs = 112 oz ÷ 65 gallon = 1.72 oz per gallon
Fabric Pot Dimensions:
65 gallon 32" wide by 18" tall
100 gallon 38" wide by 20" tall
200 gallon 50" wide by 24" tall
300 gallon 60" wide by 24" tall
400 gallon 70" wide by 24" tall
The notable variables that change between 65 gallon and larger fabric pots:
1. Considerably wider, up to 218%
2. Minimal change in height, no change in height after 200 gallons size. Only 25% taller over an increase of up to 6x the soil volume!
Shorty Soil Saver Fabric Pot Dimensions:
65 gallon shorty 38" wide by 14" tall
100 gallon shorty 45" wide by 14" tall
200 gallon shorty 65" wide by 14" tall
300 gallon shorty 80" wide by 14" tall
400 gallon shorty 87" wide by 16" tall
The notable variables that change between 65 gallon and larger Shorty Soil Saver fabric pots:
1. Considerably wider, up to 228.9%
2. No change in height until 400 gallon, even then only 14% taller over an increase up to 6x the soil volume!
Fabric pots are typically a bit taller then the advertised size and filled to the brim typically hold more soil than their advertised gallon size. The best efficiency in terms of oz per gallon of soil yield from seedlings or clones seems to be at a max root depth of 14-16".
Oxygen At The Rootzone, Finding The Balance Of Water & Feed Strength, PH To Maximize Yield:
Originally Posted by panhead
Pot size is nearly irrelevant to harvest weights as long as the plant has ample roots to uptake nessacary amounts of water & nutes , rootbound isnt an issue to worry about with plants who's life expectancy is 4 or 5 months , when i grew in soil i used 1.5 quart pots & set up a drip watering system , i was growing 4 to 5 ft tall bushes out of 1.5 quart pots , yeild will be based on useable light as long as the little pots supply adequate water & nutes, hence my using a drip feed on constant drip, my harvests were allways nearly a gram per watt , in the style of mediumless flood n drain aeroponics ive been running the last few yrs im hitting from 1& 1/4 to 1 & 1/2 grams per watt.
^source: A moderator on rollitup.
Cannabis roots love an alternating wet then dry cycle to maintain optimal oxygen levels in the root zone along with water and nutrients to maximize photosynthesis. This is why fabric pots were created, to increase oxygen at the rootzone. The fabric pot's sides can breathe and transpire to supply constant oxygen and help combat against over watering. The more drainage material you use (like perlite) reduces water holding capacity in your soil mix, also helping to combat against over watering and allowing for additional waterings/more dissolved oxygen.
When you water your plants the moving water also carries dissolved oxygen that the roots can readily absorb. Watering daily in the morning or multiple times a day creates growth rates hard to believe due to the constant re addition of oxygen at the roots when done correctly.
Oxygen at the rootzone is one of the main differences in the rapid growth in hydroponics and passive hydro like coco coir.
Over watering prevents oxygen from getting to the roots which is the worst enemy to a cannabis plant, it NEEDS oxygen at the roots to stay productive.
A good way to think of water being added to and transpiring from cannabis plants is like traffic on the freeway, you want it coming and going both ways 70mph, over and under watering is like a traffic jam that stops both directions of travel until the wreck is dealt with. The key is to find the balance between the right amount of water the plant is drinking at its current size and the max feed strength it can tolerate, then steadily increasing both over time.(irrigation keep sounding better and better right?)
People have amazing results hand watering coco coir plants drain to waste until totally rootbound in small pots and then hooking them up to irrigation.
The other main differences in the rapid growth from hydroponics and passive hydro like coco coir is maintaining optimal PH and soil biology for nutrient availability:
contain the elements plants need in water soluble pure ionic forms available immediately for uptake, they can be used in both soil and hydroponic/soiless growing mediums. The fertilizer solution's PH must be adjusted to the correct level for the grow medium you are using before feeding!
For hydroponic/soiless growing mediums a PH fluctuating between 5.75 - 6.25 is ideal since not all nutrients are available at a one specific PH level. This chart demonstrates element availability at different PH levels for hydroponic/soiless growing mediums:
For soil growing a PH level anywhere between 6.25 and 7 is ideal for all nutrients to be available for uptake. This chart demonstrates element availability at different PH levels for soil growing mediums:
come in immediately available water soluble ionic forms, "slow release" unavailable forms and both forms at the same time. The plants roots only take up fertilizer in the pure ionic water soluble forms.
The roots release acids called exudates and the beneficial bacteria along with the fungi in the soil help break down the unavailable "slow release" forms into the pure ionic water soluble forms that are available. (The beneficial bacteria and fungi digest the unavailable forms of the nutrients and excrete them into the available water soluble ionic forms, plants just cant get enough poo).
Even organic water soluble/liquid nutrients are only readily available to your plants if the PH is in the correct range. Organic nutrients are often fairly acidic PH naturally, or are made to be that way to prevent microbial activity for starting while they are on the shelf (think fish emulsion bottles going kaboom).
While you dont *have* to adjust the feed water PH for organic soil that has been buffered to maintain PH (such as when using dolomite lime) I still highly advise and recommend you to PH your feed water when growing in soil to avoid potential problems and maximize growth!
When you add acidic feed solution to your PH buffered soil the soil PH drops until whatever is doing the buffering can raise it back up.
There are natural sources of PH Up and PH Down, many of which you can actually find around the house!
Organic "pH Down":
Earth Juice Natual PH Down (made from citric acid)
Organic "PH Up":
Earth Juice Natual PH Up (made from potassium bicarbonate, approved for organic)
Originally Posted by VerdantGreen
hey Ulysses- im with you on the benefits of dolomite!
and the interests of getting this buffering/time thing nailed down I performed me a little experiment this morning.
I took a glass of water and put a tiny shot of my citric acid solution into it .
I measured the pH with my pen and it read 5.1.
(YES, I am an organic grower with a pH pen, part of a rebel alliance of heads that like to know the acidity of their water, the pHorce is strong within us – deal with it!)
I then took a half teaspoon of powdered dolomite lime and stirred it into the acidic water. Here is what happened to the pH :-
Original pH before addition of Dolomite = 5.1
1minute - pH had risen to 5.3
5 minutes – pH had risen to 5.8 – so within minutes we have a much more desirable pH plant-wise!
15 minutes – pH was 6.0 – doing its job nicely.
1 hr – pH was 6.3
2 hrs – pH is 6.4
ETA: 3 hrs - pH is 6.5
4hrs - pH is 6.6
5hrs - pH is 6.7
8hrs - pH is 6.9 - job pretty much done!
now I don’t claim that this experiment is mimicking the conditions in a pot perfectly, but I am very confident to conclude that powdered dolomite lime, well mixed into the soil, will do the job of buffering the pH of the soil possibly within minutes, certainly within hours of watering.
And bear in mind that the pH scale is logarithmic so a pH of 5 is many times more acidic than a pH of 6, and thus will react faster with the dolomite as can be seen in the experiment. As the pH gets nearer to 7 the buffering effect will slow down, but the pH is nearer what we desire anyway, and considering that the optimum availability pH for most macro and micro nutrients it between 6 and 7, the job that the dolomite is doing is, imo, exactly what we want from it.
Hope this helps.
May the pHorce be with you
Pots deeper than 16 inches take up more space than is justified by their yield. I want to attribute the difference with the larger pots to more difficulty maintaining optimum watering/feeding habits and conditions.