Hey guys. I’m curious how much your plants are drinking at their most demanding times?
How big are your containers or how large is your medium?
What medium are you using?
How many times a day are you feeding?
Drain to waste or recirculating?
How much run off do you shoot for?
How many plants per light or per square ? Looking forward to seeing what everyone else does a DOes and how much water they can get away with using. Thank you.
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I will use whatever source of water on site .
Water is the most important thing for growth but over watering deadly to plants .
When growing in soil pots or coco or super soil . Going up to 30 gallon pots was biggest I’ve dealt with lately. With these grow mediums . Soak all through then let dry all the way down . Then keep it on that cycle figuring the water moisture meter set to figure out the cannabis plants willltin point . Also reason why I put organic acids in all Rkag fertilizers . These acids buffer mostly any water source . Making nutrients available and breakin the surface tension of the water for uptake . Great topic and under watering and over watering is crucial for success
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Hey Vinny,
I’m not great with live soil and no magician without my base nutes. In my case, I like to stay with small or medium size pots and use an organic commercial drip medium peat based. Not super soil. Use salts and organics but with mulptile reservoirs. Base nutes and tea separate.
The name of my game is water as much as I can but quick drying for repeated watering.
Grow in soil peat based and water like hydro.
If you can feed your soil grown plant 2 times a day light feedings, they will go nuts.
Use synthetics but with high tech organics it sets up for bigger stronger plants.
Light feedings but more often.
Root bags and small pots can help with that.
Big strong healthy plants draw up alot more water and nutrients. Adjust accrodingly.
Act on the fly.
Kyle M
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Hi Vinny!
The thing you need to consider is that the size of the containers or the type of growing medium do not determine the plant’s water needs. A plant does not “drink” more (or less) in a big container than it would in a small 3" rockwool cube.
The water needs are determined by its capacity to transpire, this capacity is mainly driven by climate. Which ultimately means the water needs will be determined by the amount of leaf surface you have and the climatic conditions surrounding those leaves.
There are no magic bullet single value for this, however there is consensus around “an average mature canopy will use 4-6 litres per square meter.” Thing is everyone might have a different interpretation of the size of “average mature canopy”
Runoff : depends a lot on the quality of your nutrients and again the climatic conditions, as dry and hot does favor salt build ups (among many other things). A growers that monitors his grows tightly and fertilizes properly will likely need little runoff, while a blind man should aim for 20+% to keep his crop safe. keeping in mind cannabis will intake a lot of things quite easily, better control means better quality.
Drain to waste or recirculation. That choice of system is often dependent on the location of the grow op. Some cities are quite restrictive as much in the amount of water you can use as well as what mineral content the waste water can have before being discarded.
An exemple of this is Montreal, Canada they will not allow more than 20 ppm of phosphorous in the sewer. That is not much, considering the nutrient needs in P are quite high, and runoffs will carry way more than that 20ppm. Therefore recirculation can be a better choice, as long as proper water filtration systems are in place to handle it over time.
So these things really need to be assessed by the grower before even building the facility and much before choosing how many plants per light.
Good Luck and Happy gardening!
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Hey Vinny,
On a side note, your starting water is reallly important also. Testing your feed supply is critical to make sure there are not any competing contamintes that can hurt the grow. Although city water is easier to treat, the consistency can be a wide range. Reverse Osmosis is one way to ensure consistency with your incoming TDS (Total Dissolved Solids), but it isn’t always needed. A water test will determined what makes up the TDS and will allow you to decide if RO is needed or not.
With a Well Water Feeds I would recommend testing every 6 months. Water tables can change for the better, or even turn for the worse.
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Agreed…your water is a crucial element to overall plant health. Having water tests performed regularly great advice @TheWaterGuy!
@vinny, I’ll chime in my two cents here: I prefer coco and larger (i.e. 10-25 gal) pots. This is open to critique, but IMHO the larger pots minimize my need for frequent watering. I veg from 4-6 weeks with one transplant and flower my gals when they are 2-3 feet (1 meter) tall. With the 25 gal Geo Pots, I am able to minimize my need to water/feed to once a week and I harvest very happy plants in the Sonoran Desert. With the 10 gals, I water/feed just about every day.
Always drain to waste for me. I like 10% runoff, but many growers might argue that isn’t enough. Much easier to cut down on water-borne pathogens by starting fresh. Also, if you’ve ever fought the scourge of pythium, then you know what I am talking about! 29%-34% H2O2 will be your best friend if you decide to recirc your res!
Hope this helps! Here to answer any additional questions you may have! If you want some recommendations on some products I like, please feel free to PM me and we can have a good chat. 
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Is there a min and max water usage for a mature plant?
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Plenty of tables recirculating (not talking DWC) with no PM, mold or pythium (all humidity related). What I have seen by transitioning to recirculation in some specific cases is a reduction in those problems, without H2O2.
Why? Because excess nutrient (read moisture) is being pulled off the table and out of the room.
Also, the only sickness ever seen with these systems was once, due to a bad batch of nutrients.
I’d love to see how much you feed your plants in a week and see how it compares. With storing the nutrients in your pots you are adding moisture into the room, so the dehumidifiers are working more to reduce that. I would expect an increase in issues with the above regardless of recirculation.
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Never use municipal water without RO, especially if you are cultivating a medicinal. Their so-called “flouride” is not naturally occurring (it’s a waste from aluminum manufacturing), and is finally recognized as a neuro-toxin. Then there is the matter of pharmaceuticals in the water as well.
Plus, any water with more than 50 ppm will likely modify how your A/B nutrients combine.
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– In my opinion, the larger the pot the more problems you have. Like pythium, which likes the moisture if the roots are too wet for too long.
– How often to water is easy, especially if you are using a smaller pot. Never water all the plants at the same time. You simply lift each pot. If it is heavy, don’t water it. If it is light, water it.
– Drain to waste.
– It is really simple.
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While your technique is good for a small cultivation @tamarindotradingco, something more efficient is needed for commercial scale crop production.
With the recirculating systems I work with the surest way to know what the plants need is to monitor the runoff. Since you are recirculating there is an endless supply from the plants perspective. When your runoff ppm drops and stabilizes, feeding is done - usually 50-100ppm. If ppm increases then you are heading for nutrient lockout and need to flush.
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– I was not talking about a small cultivation. I am talking about plants in 2 gal pots in large rooms. Worst thing to do is over water a plant. Only takes a second to lift a plant as a worker goes down the line with a wand watering the plants. Also, it gives them a second to look at that plant and make “eye contact”. with it and look for signs of trouble and spot that trouble early. Slowing workers down is one of the biggest problems I see. They will walk right by the early stages of a spider mite infestation and never see it. An ounce of prevention is worth a pound of cure.
– As I said, “in my opinion”. We are all giving Vinny our opinions and various methods. He can pick and choose from the information provided and go in the direction he thinks is the most simple and/or best for him. A little piece here, a little piece there, pretty soon it all starts to add up.
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I see, so you are sampling the plants as you hand-water.
How many plants are we talking in a large room for you?
How many man-hours to hand-water that crop per day?
Hand-watering 50 plants in two 4x8 trays is an absolute minimum of 5 minutes. Multiply that out to 5,000 plants (tightly packed 250 lights in five rooms) and that’s 500 minutes, over 8 hours. A crew of four would take over two hours and you will want to stagger the lights so that those last plants aren’t more moist when the lights go out and you risk mold in that last room as the moisture accumulates over time because it’s only getting ten hours with the lights on after watering. In addition, you will have no clue, other than your watering rule of thumb, about the potential for nutrient lockout until the plants show it, and are now distressed impacting their yield.
With a 95% labor savings over hand-watering, and the ability to dynamically tune your feeding times to the plants requirements, irrigation systems are quickly becoming the rule. While there is no one objectively correct method of cannabis cultivation, there are objective best practices for an efficient, high-yielding cultivation that is able to make a profit.
That said, you are soooo right on about the need for eye contact with the plants. I liked to have a cup of coffee with them before feeding. It was too hard for me to pay attention to the plant in detail while I was counting how long I was holding the wand for this plant, and worrying about whether I missed the plant behind it. With pump-driven irrigation, there is plenty of time for attention on the plants.
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… My answer was tailored to Vinny. I looked at his profile and checked out his facebook page and then tailored my response to his needs. The system you are selling would be overkill for him. He is not concerned with high yield. He sells clones. He wants quality on a much smaller scale.
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I appreciate everyones input on the topic. to clarify I am a clone only operation now, but we are building a commercial operation to flower in. its 3200 sqft and we will have 4 grow rooms total. 3 flower 1 veg. looking like 3- 5x20 benches in each flower room with 12 lights and 16 plants per light.
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… Now that things have settled down, let me add the details of my system for larger grows. You don’t need to check all the plants every time you water. This cuts down on the time you have to spend on watering by hand, and keeps you from overwatering or underwatering each individual plant.
… PAPER CLIPS. Office Max, and other such stores, sell large paper clips which are coated in plastic in various colors. So, you go in in the morning and check all your plants by lifting them. Just takes a second. If they are light, you water them. If they are heavy, you don’t. As you water them, you put a red paper clip on the rim of the pot. The next time you water you can see which ones you watered last time. So, you don’t need to check those. It cuts way down on the time it takes to water the room. This time, when you water, you put a blue paper clip on the rim. The next time you water, any pots which don’t have a paper clip probably need water. Put a green paper clip on them when you water them. Depending on the size of your pots, the red paper clipped pots may or may not need water the next time you water. If not, the next time use yellow paper clips. Now you have a system where only the plants which need water get watered and you don’t need to check all the plants all the time. It is a beautiful thing to behold.
… The big advantage of this system, compared to automatic systems, is that you are not watering plants which do not need to be watered. We all know how much plants hate having “wet feet”. It leads to all kinds of problems.
… Since you are not watering all the plants at the same time, humidity in the room does not skyrocket.
… When you flush a plant, put a white paper clip on it.
… This gives you a chance to experiment with a few plants. Let’s say you want to try adding ground garlic to a plant to see what happens. Put a purple paper clip on it so you can keep an eye on it and see what happens.
… It helps you spot anomalies in the room. Say you water on Tuesday (blue paper clip) and all the blue paper clipped plants in one part of the room take an extra day to dry out before needing to be re-watered. You might ask yourself, what is going on in that part of the room? Cold spot? Lack of air circulation? Infestation of some sort? It helps you spot problems early.
… There are many advantages to hand watering. It does not need to be time consuming, with this system. It will only cost you the price of some colored paper clips. It allows you to have a ‘mind meld’ with them and become one with your plants.
… This is my opinion, and I am welcome to it.
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That’s a great system for hand watering. Cheap, effective. Thanks for teaching us your technique
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Exellent method. You can’t get anymore simple than that. Thanks for sharing.
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Trying to make sure I understand you correctly…you recommend watering each plant what, every other day in over-sized pots leaving that moisture on the table?
We’re talking bloom rooms here, not clones.
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… If you will read what I said you will read: “I am talking about plants in 2 gal pots in large rooms.” That was in my second post to this thread. I never mentioned over-sized pots.
… Personally, I never leave moisture on the table. I suck it up with a vacuum. I never mentioned leaving moisture on the table.
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