Home Forums Cannabis Cultivation how much water should i give my plants

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    • #6310
      cannaJ
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      Points: 244

      i have two 20g pots, iv been giving them water(1g at a time) every few day or when i think they need it. only thing im worried about is what happened my last grow which is i didnt water enough. i know this because i dug my roots out and found they only grew on the outside of the bin i had them in or where the water flowed. i dont want it happening again this grow so i want to get them on a water schedule but also dont want to get to a point where im over watering them. i herd this water moister testers dont work so do i just trust my gut?

    • #6319
      Somatek
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      Points: 6,637

      It’s hard to answer this without knowing more context like how big the plants are, what the temp/humidity is, etc. As a rough guideline I’d expect to need around 4-5gal of water to fully saturate a 20gal pot adequately assuming the plant is full sized.

    • #6338
      Brucewaynegardens
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      Points: 253

      You have to consider dry backs etc. I only water with 25% of the pot size with organics. Watering to runoff is with salts is another story . So much depends on your style of growing

    • #6352
      Keith
      Participant
      Points: 6,116

      I always read about 1/3 the volume of the pot.  But honestly I’d just go with whatever soma recommends, lol.

      • #6413
        Somatek
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        Points: 6,637

        I don’t actually recommend anything as I have no clue about the context.  Maybe their soil mix is 90% perlite and a 20g pot will only hold 1 gal of water.  They could have a tiny little seedling growing in a 20gal pot which would require a completely different approach.  Which is why I gave a vague, general answer with specific qualifiers like “assuming the plant is full sized” as I definitely wouldn’t give a seedling 4-5gal of water.  Vague questions without context can only be answered in general terms that may or may not be relevant.

      • #6504
        cannaJ
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        Points: 244

        well the mix is roots organics 707 the plants are posted on my grow jounal they are about 2-2.5 ft wide 8-10″ high temp is 72-78 rh is 68-75. i gave them 1g of water each about every 3 days but some times its sooner or later as i have to buy water because my tape water is contaminated.

      • #6520
        Somatek
        Participant
        Points: 6,637

        Sounds like they could probably use more water, if I see your grow journal I’ll have a look but I don’t really go to that section often.

    • #6584
      Brad104
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      Points: 786

      I would water and seeing how you can’t pick up a 20 gallon pot,like somatek said it’s vague but use your index finger and do your finger test after you give it whatever you give it is the soil still dry at the first inch or inch and a quarter down that’s my best advice

    • #6626
      Atom
      Participant
      Points: 691

      I run 5 gallon pots and during full swing of flower they get about 2 gallons every 4 days. It don’t start out that much though, you don’t want to drownd them to much at first. The roots will always want to search for water and if there’s always lots of water available they will get kinda lazy and not expand as much as you want.

      Like others said its hard to judge there’s alot of different factors. The best way to tell is just lift the pot before you water and after. Go by the weight until you get into regular water intervals. If you have to bust out a scale. You’ll probably be only watering once a week in 20s and something like 3-4 gallon when in full swing if flower but I’m just guessing.

      • #6679
        Somatek
        Participant
        Points: 6,637

        Lifting the pots before and after works great assuming their actually getting saturated; with chronic under watering the hydrophobic nature of peat can make it hard to re-saturate, often has dry pockets that don’t absorb water even when a lot is dumped on which confuses beginners as they see run off with barely any water added and the pots don’t change weight much.  Which is where I learned in the grow shop the better way to learn is to keep a pot full of bone dry soil and another filled with completely saturated soil by the grow to compare their weights to your growing plants.

        Although with a 20gal pot I wouldn’t want to be lifting that up to check, my back is screaming “no” at me just typing about it lol.

      • #6709
        Atom
        Participant
        Points: 691

        O shit can’t believe I didn’t consider that lmao.🤣 I’ve ran into that problem where soil wouldn’t fully saturate from a bag of ffof. The way i water I give them all a little, wait 5 or 10 min, come back and a little more, and wait. Then there good to go ahead and fully water. Sometimes some will run out the sides but it will soak it back up.

      • #6712
        Somatek
        Participant
        Points: 6,637

        Usually that’s enough but with seriously dried out peat I’ve seen it float on top of water for hours until finally starting to soak in.  Which can easily happen if someone’s growing an auto seed in a big pot as a beginner or using soil from a bag that’s been open for awhile and dried out.  Help people long enough and you run into all kinds of weird situations.  I was looking at a post on reddit where the grower had nute issues with his young plants in 4″ pots.  The climate seemed decent but he was describing having to water daily and the pots constantly drying out no matter what he did.  After asking enough questions it turned out they were on a heating mat left on all the time, so even though the air temp was good (humidity was a bit low) the soil was way too hot and drying out too much limiting how much the soil would actually hold.  The smallest things can make a huge difference as everything is interdependent and needs to be considered.

    • #6691
      Keith
      Participant
      Points: 6,116

      20 gallons would be pretty heavy to lift.

    • #7160
      Brad104
      Participant
      Points: 786

      That’s why I suggested the finger test or a moisture meter hell it’s going to be one big dude lifting full 20 gallon pots that’s for sure man,but as @adom said maybe a scale but even dry I would not know exactly but it’s definitely a few hundred pounds at the least I’d figure

      • #8028
        Somatek
        Participant
        Points: 6,637

        The issue is neither the finger test or cheap moisture meters give an accurate idea of whats actually going on in the soil, especially in peat where poor watering practices can lead to dry pockets that repel water and become dead zones for growth.  The bigger the pot the more on point your watering needs to be and once you’re past 5-7gal it’s impractical to lift then so you really need to rely on your skill instead.

    • #7997
      Racky
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      Points: 2,469

      I water my 5 gallon pots with a gallon every other day until the slow towards the end of flower

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    • #8036
      Brad104
      Participant
      Points: 786

      I honestly think that is a bit much in my opinion @racky but I’m of high hopes that soma will chime back in on this I think it’s a bit much,but it may not be.Are your leaves showing any sighns of overwatering? Any how that’s just my opinion but Im hopefull that someone else will let me know if I am wrong ok buddy so take my opinion with a grain of salt,if your leaves are not showing signs for overwatering them you are fine I just think that is a bit much but I don’t claim to know nothing my friend your plants looked good every post that I have seen so you are doing something right,so anyway I hope you are straight, and best of luck @racky

      • #8039
        Somatek
        Participant
        Points: 6,637

        I don’t know how much @Racky should be watering his plants, there’s too many unknown variables to make any sort of guess.  It’s not up to other people to tell you how to grow, at best we can explain the variables and help someone understand how to read their plants so they know how to meet their needs.

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