Please help explain pot sizes and amendment ratios

[Spaceman_Spiff]

Ok so this is confusing for me. I have been growing a long time. It wasn't until I started organics that I needed to understand ratios of soil and amounts of dry measurement for organic matter.

Here's my question maybe somebody can enlighten me.

There are various industry pot sizes yes? yes. #3 #5 #7 #10 #15 etc. Along side that you have amendment ratio recommendations per gallon for container growing.

So according to my local experts at the horticulture shop. If you have a #5 pot that means it holds 5 gallons of soil by volume. Even though if you measure the pot it only holds 3.3 gallons. So I tried to look this up online and could not really find the information. So he says if I'm measuring amendments in a #5 pot then if it says 1 TBS per gallon it means I should add 5 tbs. of amendment to the 5 gallons of soil. But by my measurements I should add 3 to the 3 gallons of soil that are actually in the pot. He says all of these measurements are based on an industry standard that was set many years ago and I shouldn't over think it but maybe somebody around here can explain this to me so I can act more appropriately and more accurately in how I amend my soil thanks.

I did a search... if this information is on here somewhere feel free to link it thanks again.

p.s. hold a #5 pot next to a 5 gallon bucket from home depot.... they are clearly different sizes hence my confusion.

 

[exploziv]

Well pots are measured by total volume, and we leave an emptyspace above, so you would have 10-15% missing just from that. I never supposed the # pots are gonna be any rounded number in gallons or liters. I always measure when unsure.
My "6 l nursery pots" hold 4.6 real liters of water, so there u go.. its always off. I think they just aproximate the size based on the closest regulated geometric shape then can find, but the pots are tapered and so on so they end up other measure than calculated. The round ones you see at the garden shop they were so off that they started just giving the max diameter and height now. At least that means you can't buy one marked 50 liters that only fits like 36 liters, as It happened to me in the past. So all good! Btw, if using agood balanced recipe of slow release stuff, adding a bit more amendaments than called for should be no problem as well. So just get some measuring cups or something and start mixing. You don't have much to worry about. There is always error even in measuring them out, not even all bags really got as much as they say on the bags, and some ammendamendaments even have varying contents by source or brand, so just don't add nutrient rich stuff like compost in excess, the others you can go abitfreehand on, as long asyou keep close to what the recipe calls. Its not exact science!

 

[Spaceman_Spiff]

hey thanks for the reply. I guess I got to loosen up a little bit with organics. The guy at the horticulture shop was explaining that it is all based on an industry standard set in the past. So if I were to buy a "standard" bag of soil that will contain "14 gallons of soil" which will fill two # 7 pots perfectly. Even though the actual measure of a seven gallon was around 6 gallons of volume. So its like a system of math with specific units developed only for this specific industry. And then when the companies that make amendments put measurements on the box they use this "industry" math.

On a side note: if you consider how you measure liquids vs solids in the kitchen a cup of water is not the same measure as a cup of flower right? And even the measuring devices for liquid vs solids have a size variation so maybe this translates to soil volume in someway? I do not know, anybody around here know how to do math?

It was also mentioned that if you measure by square footage that also changes your formula.

If you would like check out this link to a pot volume calculator and understand why this adds to my confusion.

Pot Volume Calculator - GrowDF.com

For most setups, it is common to have 4 dragon fruits in a 20 or 25 gallon pot or 2 DF in a 10 gallon (#15 nursery pot).

growdf.com

 

[Creeperpark]

Follow a good organic soil recipe to the toe and water the container until you start to get run-off and stop. Measure the amount of water used and that's all you need to know with organics. Don't over water to run off or you will lose a good portion of nutrients that can be used later by the plant. Knowing the amount of water a soil mix will hold in any container is key when using water as a nutrient catalyst.

 

[Burn1]

In my experience, the size of your containers determine how frequently you have to water. If you had a 55 gallon barrel of organic soil, you would have to water less frequently than if you had a 5 gallon bucket. Now, if your organic food was in the water, or in the soil, that would require some math. Fuck that!. I used 4 gallon square mayonaise buckets I got for free at my local restaurant. Drill a few holes in the bottom and there you go. It doesn't matter if you use blood/alfalfa-bone-kelp in the soil or guano tea in the water, you have all bases covered. Just water as needed. I hope that helped you. Please reply.
Burn1

 

[f-e]

It's all nonsense.

From the top, a #1 pot is classed as a gallon, and holds 3L of water
A tablespoon isn't 5 teaspoons, it is 3
Who's spoon? an any case, the US one is almost 25% bigger than imperial.
The guys in the shop were taught metric, and don't have a clue about a system that went out of use 50 years ago. Why are they holding on to that ****


You are on the right path measuring your pots properly. If the amendments supplier can't do as good a job as you, find a supplier that's this side of the 70s


I wouldn't talk with a child about cups and spoons. The world is metric. The more scientific this gets, the more people hanging onto the old numerical systems make mistakes. The old system has nothing below a teaspoon, while we are looking at feed in thousandths of a gram. Metric is so elegant, you can't make any of these simple mistakes.

 

[Dr.RedWhite]

Metric is a half arsed method of measuring. No option for fractions, most of the time the increments are too small. We should go back the the inch system. Simpler and more useful.

 

[Creeperpark]

In-plane commercial greenhouse grows the seeds are usually started in plug trays that hold 72 plugs. As the roots expand outward and feel up the trays they are up-potted into 4-inch containers. Depending on the type of plant the plants are then moved into 6 or 10-inch pots. This happens in just a few weeks. The reason up-potting is used is that it's the most economical and produces the most plant for your money.

The difference between a successful greenhouse and one that's not is "water management". If you can not manage the watering requirements for plants correctly your plants will end up in the infirmary. Greenhouse growers use different pot container sizes for this reason. They only do what has already been proven to be best by trial and error. I have found that indoor growing is not any different.

 

[troutman]

If I plan on transplanting I like to do so as soon as I see a root coming out
the bottom holes. The sooner you do that the less rootbound the plant is.

 

[Creeperpark]

Organic growing is much slower than peat or coco grows. I start with dixie cups and move up to gallon pots. When I see sex on the plant I will up-pott from a gallon to a 3 or 5-gallon container depending on the soil type. Only 3 up-potting are needed in a grow.
If you know your container's "water holding capacity" and measure the amount of water you use, you can keep organic nutrients longer. Save soil and use less water.

 

[Ca++]

I go up a couple of inches at a time, as soon as they can't get through a day on a single watering, or they show a deficiency so need more food/soil

Before 12/12 I want them in a final pot, which might mean jumping a size. This is because running out of food during bloom, can't be fixed with repotting. After a few weeks, they are out of vegetative growth and into reproduction. So won't find the extra feed from a repot. This is why people reach for the feed at this point. Which is the opportunity to rebalance the soil towards a better bloom ratio as part of your crop steering efforts

 

[Switcher56]

If I plan on transplanting I like to do so as soon as I see a root coming out
the bottom holes. The sooner you do that the less rootbound the plant is.

or... one can use cloth pots

 

[goingrey]

Ok so this is confusing for me. I have been growing a long time. It wasn't until I started organics that I needed to understand ratios of soil and amounts of dry measurement for organic matter.

Here's my question maybe somebody can enlighten me.

There are various industry pot sizes yes? yes. #3 #5 #7 #10 #15 etc. Along side that you have amendment ratio recommendations per gallon for container growing.

So according to my local experts at the horticulture shop. If you have a #5 pot that means it holds 5 gallons of soil by volume. Even though if you measure the pot it only holds 3.3 gallons. So I tried to look this up online and could not really find the information. So he says if I'm measuring amendments in a #5 pot then if it says 1 TBS per gallon it means I should add 5 tbs. of amendment to the 5 gallons of soil. But by my measurements I should add 3 to the 3 gallons of soil that are actually in the pot. He says all of these measurements are based on an industry standard that was set many years ago and I shouldn't over think it but maybe somebody around here can explain this to me so I can act more appropriately and more accurately in how I amend my soil thanks.

I did a search... if this information is on here somewhere feel free to link it thanks again.

p.s. hold a #5 pot next to a 5 gallon bucket from home depot.... they are clearly different sizes hence my confusion.

You are not confused at all.

The "number" container are typically smaller than the volume in gallons and the volume is not even standardized.

I would follow the amendment recommendations to real volume, not pot number. It's unlikely that they have been optimized for these #1 #3 #5... containers. A lot of times there is even no container, just a hole in the ground. And even with the containers makes sense to mix up a larger batch in one go and then fill up the pots from the big pile.

Then again, they are just recommendations and it's not that exact. Often my ratios are based on the formula "amount of amendment I have in the garage divided by the amount of containers I plan to fill".

 

[CrushnYuba]

So most the time when they say gallons for pots it's not actually a gallon. It's called a "trade gallon". Trade gallons are about .7 of a gallon but it's really whatever they feel like. Lot of times they will list actual volume also. I hate that trade gallon shit.
Amending by volume of soil, kind of makes sense but not entirely. It usually only is pot growers that do that. Most other farmers use per sqft or acre. If you ever see a recommended application for a dry fert on the back of a bag, it's by area not volume of soil. You can grow bigger plants in small volumes of soil. You can also grow tiny plants in large volumes of soil. 1 sqft of canopy needs the same amount of food and water delivered no matter the soil volume. Other people's recipes don't translate unless you have a similar soil volume to canopy size as them. Do you see what I'm saying? I amend by canopy size instead of by soil volume and it's more true.
You can grow any size plant in any volume of soil and it needs what it needs. I wouldn't stress on gallons. Same goes with water. A given plant size needs the same amount of water no matter the soil volume. It just needs smaller amounts more frequently because u don't have as much media to retain moisture.

The only thing is, you have to use common sense. If you try to put tons of food in a tiny amount of soil, you will get signs of over fert in the beginning. So if you use tiny pots, some of that stuff that's will have to be top dressed later in the grow if it's not super slow released. Mostly stuff like nitrogin and salts like potash.

So if u see a recipe u like, either copy there entire setup and method, or do some math based on their canopy size.