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    Pot size

    What size pot do I need for this plant?
    this is the same (problem) plant that I submitted under the title “sick plant”, where I was advised that it could be saved, and one of the steps was to bury the stem underground and let it sprout roots. This may determine the (large) pot size just because of the depth requirements, but if it didn’t, what is the rule of thumb for determining pot size? I believe that the canopy diameter tells when to go to a bigger pot, when the canopy reaches the pot diameter, but what is the maximum pot diameter based on the canopy size? (I just read that you don’t want the pot to be too big, that the plant cannot use the water fast enough.)
    Also, what type pot is best, clay, plastic, other?
    Click image for larger version  Name:	IMG_1406.jpg Views:	0 Size:	2.17 MB ID:	630609
    Last edited by Brwnthmb; 09-06-2024, 04:48 PM.

    #2
    Fabric pots are all I use even outdoors. That's what works for me. I'd pot her up in a relatively dry medium and tear the current pot down the sides so the roots can find air with just a touch of damp. And watering around the plant in a circle will promote the roots to extend and explore new area.

    Comment


      #3
      You need a big one. right above your post is a guideline that says "Growing Basics" . Start with that read first.

      Comment


        #4
        I use black plastic pots both outdoors (only when I may need to move them) and indoors.

        I was a minimum 13gal pot guy but now I am using 7.6gal pots and still getting a pound a plant indoors but the coco ends up being one big root ball and you can't really reuse it.
        5 gal pots for autos works well for me.

        I do not transplant as I don't like to stress them, except for clones of course.

        You've probably been told already but that plant needs a lot more light and a good breeze.
        Flower Room: 11' x 7' x 7.5'H, 480w AC, 13gal/day dehumidifier, 1.5gal ultrasonic humidifier, 60gal (27gal usable) nute tank, 16" pedestal fan & 18" wall fan. Lighting and climate automated. Hand watering.
        Veg Cupboards: ​​​​​​Two 4x2x6H cupboards. SF2000 Evo in one SF7000 in other. Climate controlled and automated. Hand watering
        Aeroponics Low Pressure Bucket: 20W LED. 5 clones & 20W LED 11 clones
        Lights: Mars Hydro FC-E1200W, SF-7000, SF-2000 evo in flower room.
        Medium: Coco/perlite, 7.2gal pots, no drains
        Current Grow: ​​​5 x Photos Franklin's Orange Zkittles x Sour Diesel in flower room, 3 Franklin's White Widow x Sour Diesel Clones, 13 x Orange ZkittleZ x Sour Diesel clones in Aeroponics buckets x 2.
        Last Grow: A mix

        Comment


          #5
          Originally posted by Bluey View Post

          You've probably been told already but that plant needs a lot more light and a good breeze.
          Click image for larger version

Name:	IMG_1406.jpg
Views:	140
Size:	2.17 MB
ID:	630722 your recommendation for more light and a good breeze.
          1-what do each of these recommendations correct, exactly?
          2- just guessing; I’d say that since the plant is leggy, reaching for light, you need more light, and the breeze is for the same problem? It promotes a stronger (and shorter) stem?
          I may be answering my own question but I don’t want to assume that I know the answer. You could be making an important point that I am missing completely.

          Comment


          • Smallgrow
            Smallgrow commented
            Editing a comment
            Nope, don’t think you missed anything, your answers to your questions were exactly right

          #6
          Originally posted by Speedygreen View Post
          Fabric pots are all I use even outdoors. That's what works for me. I'd pot her up in a relatively dry medium and tear the current pot down the sides so the roots can find air with just a touch of damp. And watering around the plant in a circle will promote the roots to extend and explore new area.
          is the “fabric pot with (relatively) dry soil around the small root ball of the plant, and watering only under the canopy” your basic method? And then the watering circle gets bigger with the canopy diameter?
          If so, how do you know when you have enough water but not too much? And how do you know it is time to water again?

          Currently, with the peat cups, I water when the surface is dry. I bottom water until the surface is wet again, 5-10 minutes.
          For the clay pots (8 and 10” diameter) I water when the surface is dry. I am now trying to keep the watering diameter equal to the canopy (sort of) but I don’t know how to judge when I have watered enough.
          So how do you know when you have enough water but not too much? (Same question as the one above.)

          Comment


          • Smallgrow
            Smallgrow commented
            Editing a comment
            It takes time and experience to master watering. I know nobody wants to hear that answer, especially when your starting out, I didn’t, but it’s the truth. There is no silver bullet , every plant, medium, and environment is different .
            I have seedlings about that size in solo cup sized pots , in my environment 20-22C 65/75% humidity I will water about 10ml at at time around the stem, and every couple times I will do an additional 10ml around the pot perimeter. This may be every two or three days
            If you haven’t read through all the watering tips on the main site you should.
            To put it in perspective after years of growing, I focus mostly on watering as a source of my issues. No additives or products will help you if your watering is off. I feel a tonne of people chase deficiencies with all kinds of additives , when really it watering that is the problem

          • Speedygreen
            Speedygreen commented
            Editing a comment
            Smallgrow is right. It takes experience. But u can water very little or not at all until the leaves start to droop and that should help u understand how much moisture deep in the pot it takes. It's just a learning process that sometimes makes u feel like you are hurting the plant but I assure u when it needs water it will ask by drooping leaves. Hope this helps bud. Happy growing

          #7
          I’m trying to respond to #6-1 and #6-2, Smallgrow and Speedygreen concerning watering. I reread your comments and I was very surprised to find that you had said that 10ml of water around the stem every 2-3 days (plus 10ml outside of the canopy every couple of times) is a starting recommendation.

          I read everything I could on watering and the advice was all over the place, but mostly they recommended much more than 10ml every couple of days.

          If the 10ml around the stem every 2-3 days, followed by another 10ml outside this every other watering sounds about right just give the word. I just want to make sure that I heard you right. I have repotted leggy plants in large clay pots up to the bottom leaves and they are doing well. However I’m concerned about what happens when the saturated soil dries out, i e if the regiment of 10 ml will be enough to sustain a healthy plant in a large (10” diameter) pot.

          edit; I can measure 10ml but it is using a graduated cylinder from my chemistry supplies. The smallest graduation on my watering pitcher is 200 ml. That’s another reason I question the 10ml.

          edit2; thanks for the 10ml recommendation. That is something I never would have found out on my own. For one I have never grown a house plant before. Secondly, I had read the recommendation of one inch (of rain) per week. For a 10” diameter pot that is 1288 ml.
          Last edited by Brwnthmb; 09-16-2024, 01:03 PM.

          Comment


            #8
            Watering correctly always seems to be the first hurdle most newbs run into. Here's how I water my plants.

            I'm typically in a 5 - 10 gal cloth bag. My suggestion to you would be to use a 7 gal cloth bag. A 5 will work but 7 tends to hold onto water a little longer so you don't have to water as often and the extra biomass keeps most deficiencies at bay depending on how you are fertilizing your plant.

            I water the outer perimeter of the pot first with about a 1/4 liter of water making sure to water slowly to counteract the hydrophobic conditions the soil will be in when you let it dry. If water starts to come out the sides I'm watering too fast and I will stop to allow the water to sink in and absorb into the media before I continue. I'll do this until I see water coming out the bottom of the bag. Once I see this I will water around the stem and where I think the root ball is around the stem and water it slowly until I see water coming out the bottom of the bag. This should saturate the entire media so that you don't have dry spots in the media.

            Just so you know, cannabis likes a moist to wettish soil composition. Overwatering usually occurs from watering too frequently and not allowing the media to dryback allowing the roots to do the O² exchanges they need to do to keep your plant healthy.

            Read the following you so you learn more about how pot size choice, media and watering practices all work together.

            This will be a long read based on my personal knowledge, opinions, research and others work to consolidate information for our members. I'm not presenting my opinions as facts so take from this what you like. I will be putting it in subsection format for easy reference.

            First I want to make an important point to take into consideration before reading. The tap root will grow directly downwards to the bottom of the container before spreading out.

            PERCHED WATER TABLE

            What is it?

            The perched water table is basically the height of the saturation zone where capillary action and gravity cancel eachother out. This area will be saturated with water and will be responsible most growers issues with watering practices especially in soil grows.

            WHAT IS CAPILLARY ACTION

            CAPILLARY action is is the combination of the cohesive and adhesive properties of water.

            In short adhesion is water clinging to the media (think of it like wicking or soaking up)

            Cohesion is where the water clings to itself.

            So as the water is wicked up (adhesion) it pulls more water with it through Cohesion and at the point gravity and these properties cancel eachother out is the perched water table.

            This perched water table will always remain the SAME HEIGHT and will always stay saturated unless taken up by the plants or evaporates when the pot dries out. No matter the container height, depth or volume of media. So if a tall skinny container had a perched water table of 1" then a short wide one of the same media will also have a perched water table of 1". Which means the ratio of water to air in a wide pot will be higher than a tall skinny pot which will have a higher air to water ratio... keep this in mind as we get further.

            Different media's have different perched water tables. A more absorbent media will have a higher perched water table than a less absorbent media... REMEMBER THIS as it makes a big difference on pot selection for your media.

            DIFFERENT MEDIA

            Water holding capacity is directly related to the height of the perched water table so soils with more clay or silt and less sand will have a higher perched water table than those with more sand because sand is a larger particle.

            The larger the overall particles of the media the lower the perched water table and better the drainage.

            By adding things like perlite or vermiculite (while vermiculite is good at absorbing water it also improves drainage so its helpful in keeping a more even level of moisture throught the media while increasing drainage due to its size) we can lower the perched water table by reducing the wicking (adhesion) ability and creating more space between particles overall reducing the cohesion effect and inturn the height of the perched water table.

            Media's like peat based or coco have a much higher drainage and lower perched water table than soil and are therefore less susceptible to over watering but will require more frequent watering due to the lower water holding capacity.

            Adding thing like perlite or hydroton to the bottom of the pots will NOT reduce the water table but instead raise it. This is because as I said the height of the water table will not change for a given media. So if you add things like that to the bottom you are essentially just moving the water table up.

            Basically the larger the particles IN the media the better drainage and lower the water table.

            If you want to see the height of your perched water table use a clear cup with drain holes fill with media and saturate it. Wait a few hrs for drainage and then come back and look. You can see the difference in the varying media's if you want to experiment.

            If you feel you have over watered or your perched water table height is to high you can simply tilt your pot on a 45 degree angle and release more water from the media as runoff. To help visualize think of it this way if you have a perched water table of 2”. You can draw an imaginary horizontal line at that height, when you tilt the pot you have less media below that line and therefore you will have less water in the pot after tilting it.

            POT SIZE

            I have already covered this a bit but my opinion is if you are using a media with a higher water table you will benefit from taller narrower pots and if using a media with a lower perched water table the shorter wider ones may benefit you depending on your watering practices.

            I prefer the taller over wider no matter the media as I choose to water often and have a higher air holding capacity and lower water table but that can work against you if you can't water as frequently and as plants grow it can greatly increase the frequency required as the roots will be pulling the water out of that saturation zone quickly. So you may want to use taller pots for small plants and transplant into a wider one as they grow.

            You also don't want a pot that's to tall and the top portion of the media is drying out to fast while the bottom is wet.

            Let's use seedlings as an example take a solo cup or a large container... the water table will be the same height in either. I see sooo often ppl trying to water a tiny bit in circles or mist the surface and for lack of other words IT DRIVES ME NUTS. Why? Because the roots are so shallow they are not at risk of being over watered. Remember though tap roots grow straight down so we to be mindful as they grow depending on the gas exchange of the media that the majority of roots are not sitting in the saturated zone with poor gas exchange because this will cause lack of oxygen that we incorrectly refer to as overwatering which is actually the cause not the symptom.

            It's important to fill containers to the top to give us a good amount of space above the perched water table that high in o2. If you fill a solo cup halfway with soil it's likely to be sitting in the saturation zone and will not do well.


            Also going to make the point that plants will be most susceptible to overwatering when the roots first hit the bottom and spread out until they fill the bottom and start moving back up out of the saturation zone. So again it may be more beneficial to use a taller narrow pot for the early stages of growth (2-4 weekss depending on growth) and transplant into a wider pot as you go. After the transplant almost all of the roots will be above the saturation zone and it become much harder to over water. New roots will again work their way down into the saturation zone but you will have plenty above so it's less likely to over water and why uppotting as you go I see as a benefit instead of starting in a large wide container.

            POT MATERIAL

            Some prefer plastic others fabric, air pots etc.

            This can affect the perched water table by evaporation as the lager the exposed surface area the more evaporation that occurs from the media in say fabric pots. This imo has a few benefits.... slightly reducing the perched water table but more so the exposure for gas exchange that's happening and that's a good thing for o2 levels in the root zone that I feel are directly related to growth rates and I'll explain why going a bit off topic for a second.

            It's no coincidence that the fastest growing media's have the highest amounts of o2 and gas exchange.... for eg aeroponics have unlimited to rich o2 and water. Hydro similar with slightly less o2, soiless media's such as coco and I would possible include peat and last soil. If you notice they are in order of growth rates and its not hard to see the difference in thier air holding capacity in that order. And the fact that larger particles also have a better gas exchange rate. This is important because the plants take in oxygen and expell co2 in the rootzone as do the microbes on top of that so good gas exchange is important for both.

            Just a note... air pruning has nothing to do with the benefits of fabric pots all it does is signal the roots to grow in a different direction.

            But let's get back on topic of watering and how it's affected.

            TEMPERATURE AND HUMIDITY

            The warmer the temps the more evaporation occurs.

            The lower your humidity the more evaporation occurs

            The more surface area exposed to air movement (wind) the more evaporation.

            Think those don't need an explanation. But the difference in pot material coupled with these environmental factors will have an impact on your watering needs.

            The temperature of the media not only affects evaporation but also directly affect the temperature of the plant and leaf temps. This has a large impact on nutrient uptake and transportation.

            First let me say that this next part is opinion and I will gives my reasoning for my opinions. With the exception of hydro (leaving this part out as this post is about watering not hydro) roots like to be about the same temperature as the leaves contrary to what's talked about from many prominent growers in the industry but not all like Mr.Bruce Bugbee. IMO ideal root temps are the same as ideal leaf temps and overall plant temps especially since the root temps have a large impact on the plant and leaf temps. What are ideal temps imo and many studies show that leaf temps (NOT AIR TEMPS) of around 77f are most efficient. So how does a cool rootzone impact the plants negatively? Well, it's 2-fold because of the cool temps the viscosity (Measurment of flow rate) of the sap will decrease so it's harder for the plant to move the nutrients through the plant. The other is absorption, and one fact is that in a cooler rootzone the concentration of nutrients is higher (but you just said it slows absorption) well it does as the nutrients build up in the roots it can absorb less and this has a direct impact negatively on the plant. It may appear to be overwatered because the plant is now struggling to take up and use oxygen. Add that to the slowed transpiration rates and you have the same symptom many refer to overwatering which again is lack of o2. Now take a cold rootzone where the plants slow water uptake and then add the saturation zone to it and you can see the road to correction and recover is a long one and can have huge impact on growth and yields.

            So, get your pots up off the floor

            WET AND DRY CYCLES

            in soil and peat with higher water tables or with wider pots or combination of wet and dry cycles are important. This is to allow the dry back (including the uptake of water from the saturation zone) to prevent symtoms of over watering and help with o2 levels. Remember the majority of roots will end up in the saturation zone with these media's or with wider pots. Which can become depleted of o2 quickly as gas exchange is lower in water and media made up of smaller particles. This is where pot size and shape are important for the size of plant. You have a small plant in large container and there is no way it can take up enough of the water in the saturation zone fast enough to get air exposure in a media that has low gas exchange and majority of the roots. So it's important to choose a pot size that will allow for this. It's also why using the finger method to gage watering is poor and lifting the pots is much better... when they are light you know they have taken up a good portion of the saturation zone and are ready to be watered again.

            This is much less of an issue when using soilless like coco or peat/perlite.

            Comment


              #9
              Does 450 ml of water seem about right for this plant?
              I like the way it looks and I don’t want to mess it up. It was 4 days since I watered it last, and it is in a 10” diameter pot. I’m trying to get a feel for watering. I’ve never grown plants inside before. Thanks.
              edit; the soil was dry at least up to the second knuckle.
              Last edited by Brwnthmb; 09-21-2024, 05:52 PM.

              Comment


                #10
                Smallgrow
                you said that you start seedings in solo cups. Do you cut holes in the bottom for drainage? Or add rocks?

                Comment


                • Bluey
                  Bluey commented
                  Editing a comment
                  Lots of holes in the bottom

                • Smallgrow
                  Smallgrow commented
                  Editing a comment
                  Yup defiantly holes.
                  I just switched to Budtrainer seedling cups. I think they are a great idea especially for beginners.
                  I really like this company and their products. They also have a great grow guide and info on their site, you should check that out.
                  I have no affiliation beyond being a happy customer
                  Budtrainer.com

                #11
                Thanks …..

                Comment

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