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How much water is enough ?


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The most common mistake is overwatering. I'd like to know from as many people as possible what they think works best for them

Let's say you got your plants in 11 litre pots with approx. 10 litres of coco or coco/perlie - coco/soil whatever.

To make it more common let's say you add water and wait till the medium is getting real dry - I test that by lifting the pot / weight or by sticking a finger inside the holes at the bottom.

How much water would you add then, so that it is enough for at leat 3 days ?

1,5 litre

2 litre

2.5 litre

3 litres

3.5 litres


The more you water the more drainage is leaving - that may/may not be beneficial.

Imo you can do that once per month to make sure no parts of the medium is blocked - but usual with Coco/perlite it is not really needed more than once per grow.




Back to the question

half a litre daily = 1.5 litres in that case

1 litre = 3 litres.

more or something in between pick your choice 


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There are a few things that work into each other when it comes to watering and you cannot see "watering" alone and expect a solid answer that holds true wherever you apply it, it aint that simpel.


My findings when to water is when the pot is "LIGHT", but what is light ?  Is it lighter than out of the pack, lighter than 3 days, 4 days... light with Perlite is another light as when without Perlite. It all differs a bit.


The thing you need to touch base is what do you actually want to achieve with watering. Ask the wrong way round, Qui bono if you like.


I want to achieve that there is a "complete" exchange of AIR insoide the pot. That can only be achieved if you fill a conatiner with another solid to expell all old gases. Well, you cant ram steel in there, but you can water.


Now, how much water do I take to expell "old" air.  I water until at least 20% of what I put in comes out again, very simpel. Do it slowly, pre-wet the surface and let it soak in if your medium wont accept the water at first and cant hold it.


Again, measure by weight !   Some pots are REAL heavy pretty quick, some neve rget that HEAVY and tend to keep a kilo lighter ( 30L root pouches I refer to, 80%soil/20%perlite by volume, thats alot of perlite ! ) but in general you will be able to tell when it 

holds enough water and when you should maybe letit soak and drip off and pour in another 2-3L to gain some weight...that wont finally drip out but will stay in.


Now that was the "normal" watering between normal weeks, when plants are in very large containers and still young..aka conquering the pot, you can stray aside and water differently to tickle the root to grow through all of your pot. Putting in other words, it can be very time consuming to put a clone into a 30L pot and water it completely and THEN be patient enough to wait until it is a light as described above. It will A: take very long  and B: wont be a good start for your plant/grow due to A:  In that case I tend to water the outer circle once or twice to tickle the root to cover the outer parts of the large pot ( large for the size of root you put in 5 days ago ).  Usually a 30L pot under 600hps takes anywhere between 4-6 days to be light again, depending on week and strain, light and air, humidity, blower fans etc etc etc  many things come into play. YOu gotta look, think, evaluate and draw the correct conclusion.  

For example: Let's say Joe had a nice room, Joe had great ideas and a great will too :)  He ended up having 7x7 in a a square, 30L pots, so 49 total. Not a too big grow but certainly larger than most when it comes to ventilation issues, humidity and last but not least work in moving pots around.  I have him the advice to opt for 30L pots to have a larger overall plant and yield and also to stretch the cycles a bit as he was not having too much time for this. 

Well, it turned out that those 49 pots JUST fitted into the room under the 600er hps's. no inch to spare and no damn space between the pots, they really touched each other. THIS turned out to be a culprit, a curse a nightmare and what not else.

The pots stayed wet for 6-8 days with flowering plants and the whole root was not as developed in ANY of the pots as Joe and his friends were used to, they examined each rootball and none was a sgood as the grows before in merely same conditions, same pots and soil but not THAT CLOSE together.


Joe now runs a 6x6 setup with 2 inches space between each pot any direction at least and twice the amount of cubicmeter acf and doubled the amount of blowers to fight humidity and move the plants around. The cycle is now 4 days !   FOUR !

4 because of better roots = larger and more developed plants in same time frame = better yield expected   and finally allowing enough watering cycles to follow a plan, with 6-9 days between all your watering plans and calendars are voided, believe me.


You should understand watering as 1 part of breathing, the other part is letting it soak in fresh air again as water is being asbsorbed, that air is BADLY needed by your root and THUS you should never ever keep your plant moist all the time as you lock out oxygen mostly from your roots and get a really badly developed plant. #1 error with beginners, next one, #2 is too much fertilizer and #3 letting them get too dry !  Too dry is a lost day in your 63 days plan, 1 day where they wont do anything but be standing still.


Watering is as simpel as carrying a can of water and can beas complex in understanding metabolism and some physics, exceptions as always granted.


36 x 7.5 liters = 270 liters   runoff basin has 60L and is always FULL after watering   ( 60L is more than 20% of 270L ).  Thats the cross check Joe does after his work.  60L in the conatiner is proof of enough run-off to avoid salt built-up, enough to have all air expelled, enough to make you wanna have a watering slave but very good for your plants development, maybe not so good for your purse as 20+% Fertilzer is wasted...but that is part of the deal we all agreed on.


I really do not go with the idea to water a soil or coco pot every day with a certain quantum. I would have to see the plant as nice and big as Joe's to believe that works as good as it runs against all I said ( what is written in books and I just found out for me it holds its truth when you apply it ).


If really nothing goes, repot into a bigger pot, water it and be save for 5-7 days......hey...stay cool & easy ;)




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WOW, that was deep. I also 'weigh' the pots each one by hand to get an idea how much fluid is still left. Once they are rather light vs a freshly watered one I'll add water / feeding like you said. First soak up the surface, wait a few minutes, then add water, As I usually mix up 10 litre in the can I tend do be a bit too free willing with it esp. if all I got to water are 2 or 3 plants. Then it takes forever /well 5 days or longer ) till the pot is as light as it was before. I have a lot of drainage going on - all that ain't that bad BUT I think less would be moreeffective, the air going to the roots and avoiding the fact the roots are in a too damp surrounding, that as well can get too cold on top. I know it depends on various factors how fast the water is absorbed. Amount of light/heat and esp. the state the plants are in. Still there must be some kind of rule of thumb what is a good amount of water applied to say plants in the second half of the flowering cycle. In a tent 1 by 1 I can only grow 9 plants in 11 litre pots. That was when I came up with my ever producing 12/12 vy seed method - allowing me to grow up to 18 in one plant and reap 3 plants each month, just enough for a steady supply - but I am kinda tired of those low yields atm. and want to get back to the conventional method - but that involves smaller pots or it just ainÄt worth the wait and effort. With 6.5 litre pots I could grow 16 in the same space, without necessarily harvesting less on average IF everything works - But with 16 pots moving them to a bath room to water makes no sense - So I would like to find a watering schedule, thar is okay - not too much neither too few - Seems I have to pick one each time and hand weigh iit and then water them accordingly.Others ?

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That 1x1x2m tent, yeah.... there are many variants that you can do, 1, 4, 8, 16 plants...

I think the best one was with 4 bushy ones in 30L air-pots of any kind, each one around 135-150gr dry yield.


All other numbers have not dropped more yield, most less, but had considerably more work involved, weak branches, small pots..


I see the need for cont. harvest or supply, just put 1 new big one in evry 2-3 weeks so you can take one out also every 2-3 weeks with a nice yield per plant.


There are really too many ways to do it, the hard part is finding the ones that suites one best, and that does change over time, gained experience etc..  

always evolving, never a standstill

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Bam, you sould really consider going flood&drain. imo it's the best watering method, period.

first, it's ideal for 11l pots. but make sure they are ROUND(aprox fi 25-28cm) you can fit 9 in there no problem. also don't buy pots but buy buckets and drill 1cm holes. 3-4 on the bottom, 6-8 on the sides(2 levels till half the bucket)

medium can be pure coco, perlite-coco, or my favourite coco-rockwool 50/50 mix. flood it 5cm under top of the medium or just half the bucket(leave it to wick) for 15-20 minutes every 4 days(3 in late flower if having need for) and you'll be just fine. actually, you'll be fucking great!

flood and drain provides more than just "water". first it floods from bellow allowing NO air pockets in the medium. second it provides the second most important, and equally important as nutrients, "thing" that plants need, oxygen. since water comes from bellow it pushes out the old and when draining it sucks in the new. holes on sides provide more intake and allow to dry the medium more efficient. and the rockwools makes sure that coco doesn't run dry.

third, by NEVER wetting the top 5-8 cm layer you allow the plant to have their business uninterrupted. the have no.1 and no.2 as well, all jokes aside. and they do it on the top around the stem. and some weird dry "enviroment" creates that in some kind of a way helps the plant.

forth, it's practical, effective, efficient and saves you a TON on water, nutes and time. I use PowderFeed, enzymes, superthrive and supervit and that's it.

yeah and I almost forgot. by not going with more than 1.5 EC you don't have to flush as much as with any other medium. I do it in the last 2 waterings only (last week) and it's perfect.

but if you want to go all coco or pelite coco mix it's also great. same thing as above just go with more frequent watering because coco doesn't like to go dry at all. every 2 days will work fine. and make sure the water is max 20•C. roots like it cold ;)



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Hey Bam,

a side note regarding pots.


Standard pots that we had have all been drilled with "hundreds" of 4-5mm holes from top to bottom, looks like a pumpgun shot.

inside the pot we put a root-fleece from homedepot and ola----there is your home made superpot.


i have since inspected all root balls after harvest, they work exactly as a superpot or rootpouch, same good root, no circles, excellent.


the are cheaper to make than buy unless you opt root pouches, superpots are a bit too high in price and too technical.


that should also work with coco mixes, regardless,, its more air and faster cycles...lower EC a tad as it goes and evaporates quicker then.


other than that...HAPPY GROWING

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my experience has been that it can vary from mix to mix as they can have fine, medium or coarse particles and fibers at different ratios. there is wide range of different type of coco peat/fiber mixes with different water holding capacitys, water retention and air porositys so the watering cycles can change too, from twice a day waterings to every second day waterings and pot type and size effects alot too


but in general i have had 1-2 day watering cycles like jose, using 6-15liter coco pots after plant has rooted in the pot first as the first watering cycles can take longer to dry.


with the slexes that i have in 6liter regular square coco pots. advanced hydroponics of holland pretty normal looking coco coir mix of differnet size particles and fibers, ive also had biobizz coco earlier that only had the finest particles in it with no long fibers

i water the plants approx 2-2.2 liters every 36-48h l depending how light they feel when i lift and touch the medium, the cycle was around 48h on the first half of flowering cycle~ and 36h cycle more recently as the plants got bigger and in to peak flower stage

that 5th slex in 11liter coco airpot i water every 48h currently but i have a feeling it will go down to 24h cycle when that plant peaks


when i have used compost soil coco mixes at around 50/50~ ratio watering cycle has stretched another 1-2 days depending on the stage and pot size but once plant is well rooted in the pot they dry fast with coco

with the 30-45liter pot sizes ive had more like 3-5 day watering cycles depending on plant stage and type of mix ive used but ive never done them with pure coco

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Excellent reoplies and a very interesting discussion. I just transplanted 2 of the last 5 seeds sown from the SLEX + Sppecial Kush and must say it was high time to do that. Esp. the tallest was getting rootboud - since I used Sermais pebbles at the bottom I could not see the roots as usual. Anyway - One went into an old TEKU 10 litre pot with lesser holes-seems I will have to drill in a few more. The other went into my usual 11 litre square pot, which I like a lot- First there are enough holes underneath the bottom plus there are large holes 2 by 4 cm at each side, that allows to feel the medium and watch rootlets poking through. Recently I ordered a couple round 7 litre rose pots with enough holes BUt I fear they are not sufficient for longer flowering strains. As a rule of thumb I say 2.5 litres per month, so for the KUSH, this might be helpful. I will make mixes next with Coco, perlite/clay pebbles and soil, hence Igot lots of that around.

I got 5 DNA /GYO seedlings , which will go in the root pouches I ordered.

5 plants ready to flower . 2 in 11 litre pots 3 in 7 litre pots. Tent is full.


I got LIBRA Cases and ordered CANNA Slabs. I think of growing GH KUSH in these - there are 4 holes for plants - hope that works That goes into a seperate room of course.

Anyone tried these out ?

anyway 2 to 3 day watering is great. Will just test out how much water is needed to acieve that. I guess around 2 litres ?

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