I’ve used a variety of pot sizes for autos. It seems there is some advantage to a larger pot (I use fabric regularly) but I’m curious if anybody has systematically determined the point of diminishing returns. For most of us, soil and/or nutes, are the most expensive aspects of the grow. I recently read that 3 gal pots are best for a 12 week plant. I’ve used both 5s and 7s and it seems the 7s get bigger plants/yields than the 5s. Would love to know other folks’ thoughts. If there’s definitive study, can someone point to it?
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I typically use 5 gal fabric pots for autos in soil and 7 gal fabric pots for autos in coco, but I might start using 7’s all the time. My current grow is in soil, but I was short a few 5 gal pots so 4 of my plants are in 7’s just because I had them laying around, and 4 of them are in 5’s. With the exception of 1 of them, the 3 others in the 7’s are bigger plants with more and larger buds.
So I’d say 5 should be the minimum if you want big autos, and 7’s will help if you want to give them the best chance to reach monster size.
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That aligns with my impressions. Both inside and out. I do hate it when I end up with one of those little skinny girls with a single cola in that 7 gal pot. Initially, I wondered if moving from the cup to the pot, the roots would kind of get lost. Now, I’m under the impression that some plants simply don’t do well when transplanted and that if they’re not happy immediately, it doesn’t matter the size of the pot. It’s also not surprising that you didn’t find a 100% result. Every auto is unique; never really know whether it will favor it’s photoperiodic or ruderalis parent.
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I’m a very strong believer in transplanting autos. I think they get off to a far better start in solo cups than they ever can in a big pot. My autos typically get very big. It’s only once in a great while when I get a smaller one.
Here’s a link to my current journal if you want to check it out. All the details of my transplant technique is in there.
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I used 7 for autos when I used to do them, but I hands down prefer photos, and use 10 gal. I’ll likely never grow an auto again.
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Imo a smaller pot is fine for coco since your feeding daily. But bigger is better in a organic style grow. Depends more on your style.
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I find 20L to be perfect in my experience
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I’m leaning towards 100% photoperiods too bro and I started on autos and had a terrible couple experiences
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Agree completely with beginning in cups. I’ve also done a lot of pucks but you always run the risk of the roots not expanding aggressively enough. I use clear cups with couple holes in bottom and I’m able to see the root development. The trick is to let them establish but not become root bound.
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3 gallon vessels have worked well for me with auto or photo period plants. 2 plants per 2 x 4 space gives me room and the average yield I’m looking for 
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How much space one has is usually the dermining factor.
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I’m working through the same question 
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No question available space also dictates pot size. 2 Green Thumbs makes a good point. Even if the per plant yield drops in the 3 gallon pot compared to a 7, does it drop as much as an entire plant if I can get one more pot in my space? Good question.
For instance, if one gets 3 oz from each plant in a 7 and yield only drops to 2.5 oz in a 3, it makes sense to go with 3 smaller plants. On the other hand, if that yield drops to 2 oz, all I did was make more work without increasing the harvest. Although I may save a few bucks on soil.
My own experience is that staying uncrowded and allowing more light and air seems to help the plants develop and avoid issues associated with higher humidity. It’s always a bigger pain taking care of a crowded tent as opposed to one where I can simply rotate a pot and get at it without having to pull it. That argues against using smaller pots to grow more plants unless the yield drop is minimal enough to warrant it.
It remains an open question unless somebody here has systematically done this pot size experiment with a large enough sample to know the answer. Anything else is simply anecdotal and given the huge variability in individual autos doesn’t give us anything definitive.
Bottom line is that a lot of us periodically review where we can be more efficient in the process. Soil is invariably a major expenditure (yes, I know it argues in favor of hydro) and I’m fortunate I get my Happy Frog locally for under $20/bag. But over the course of a year I go through a ton because I germ and transplant for another 6 growers.
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You can grow an awfully large plant in small pot. Only difference is smaller pot will require more maintenance than a larger pot. I believe the argument that larger pot makes sense for true organic grows as getting nutrients in and available takes time. Otherwise most just don’t have the time to be tinkering multiple times per day that a large plant in a small pot would require.
For indoor grow pot size or plant count have nothing to with yield potential. Less plants will take longer to fill space, but everything else being the same the yield potential per ft² will be the same with 1 large pot, 4 medium sized pots, or 9 small pots. There are all kinds of legitimate reasons for someone to prefer one way over the other, but it shouldn’t ever be because yield will be more or less.
The most important consideration for autos is their supposed limited veg cycle. The plants grow very slow until they start to establish a root mass. When using larger pots people without the best watering habits can slow this down and cause their plants to stall. When this happens with an auto that tries to flower after 4-5 weeks they usually end up as fairly small plants. In this situation a smaller pot is typically easier to get an auto growing.
I’ve probably posted dozens of times here, but for indoor hand fed grow a 3 gallon fabric pot will do just about anything you need it to regardless or growing an auto or photo. The biggest exception to this being limited opportunities to water or feed.
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im growing autos in 5 gallon for first time. up from 3 gallon pots. One example isnt enough to even begin drawing to a conclussion, but I was personally surprised that my plants didnt grow any bigger than previous grows. I didnt do anything different to encourage them to get bigger, but just assumed they would by default of having more soil and larger roots. I guess I feel that it could make a difference if you know how to really push the plant to its max potential during veg stage.
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This is helpful. If I understand correctly. Pot size doesn’t impact yield as much as maintaining the proper environment does. Since a 3 gallon pot is going to begin with fewer nutrients in the soil, the need to properly feed goes up. So that 3 gallon pot will get the job done. Just might take a bit more work to get it right.
You also mention in the third paragraph how that smaller plant that does not vigorously veg is usually due to improper watering. In your opinion, is this normally due to excess or shortage when using fabric? I always assumed those smaller plants were usually those that got stressed during the transplant from cup to pot. Is this just another way to temporarily shut down the veg process early in the game?
Sounds to me like that early veg period right after transplant is really critical to the end result. Keep that transplant happy and you don’t lose an important chunk of the plant’s short life.
Be curious if anybody tracking this wants to weigh in with specific tips in this transition. I’m sure I can find comments on the blog but those responding have all been through this to some extent.
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A lot of good stuff here. I agree with a lot of what folks are saying. As autoflowers become more popular the techniques are getting better.
- If you use soil make sure to put something in there that will allow the roots to travel. With my experience with them what I’ve found is root blockage triggers flower. So if the soil is compact the roots won spread. I do Organic compost with perlite, and coco and a little soil like 5-10% 20% worm. casting. at the very bottom O add in my flowering nutes. So all I do from that point is water.
-Fabric pots is what I recommend for autos, if the median is airey and allows the root to travel, once the roots hit the sidewall it will automatically air wick the roots for you to keep the plant growing and in veg longer. Now if you want even bigger autos than make sure you have air flow under the bottom of the pot also. So thae roots will get air wicked wgen they get to the very bottom and will have the plant go a little longer.
-Thr problem with transplanting auto isn’t always that it will kill the plant, but that once the roots hit the bottom of the cup it’s going to stunt the growth and you will have a quick 3-4 week flowering plant for sure. But if you want the most out of your auto plant it in its grow median at seed and don’t water directly in the center, Water along the edges about a inch and a half to 2 inches from the center of the plant so the roots travel out in search of water for tge first week or 2 spray the leaves during this time. Jut remember root gets blocked flower will start. Experiment with different medians that will allow roots to travel. My next grow will be in a 2 and a half foot tall bag that I grew a photo period in that I over watered the first time then watered again a week later before I realized it never dried out. I am currently 3 weeks into flower and have not had to water once since week 3 of veg, I flipped it week 7 of veg and now 3 weeks into flower. So thats a total of 8-9 weeks of not having to water and the plant is doing great. So I want to see if its a fluke or not. So If I put an auto in that same process do I not have to ever worry about watering? Hmm Below is an autoflower I grew a while back 5 gal fabric.
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Close I guess. I’m saying that simply limiting factor to pot size it doesn’t really limit much or at all. The problem is trying to keep something like root mass the size of a solo cup with the same amount of water and nutrients as a 5 gallon pot is very difficult. But it’s a lot easier to if the comparison is something like a 3 gallon pot in comparison to a 5 or 7 gallon pot. The 3 gallon pot will just deplete water and nutrients faster, so you have to feed/water more. If someone were to treat exactly the same then it’s reasonable to expect the 5 gallon pot would do better.
I may not have conveyed my thoughts clearly. I was just suggested that sometimes poor watering habits stall plants and it’s easier to water judge how much water young plants need in smaller pots. Its fairly common to see very small autos flowering at less than a foot tall in large pots. These aren’t necessarily dud plants, just took to long for root ball to establish and start growing properly before they transitioned to flower.
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I started using bags that look like coffee filters for my seeds then drop that entire thing into a 3 gal. I found I was now using the full 5 gal with the roots I am getting.
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“This is helpful. If I understand correctly. Pot size doesn’t impact yield as much as maintaining the proper environment does. Since a 3 gallon pot is going to begin with fewer nutrients in the soil, the need to properly feed goes up. So that 3 gallon pot will get the job done. Just might take a bit more work to get it right.”
I totally disagree, when dealing with Autos. That smaller pot will cause the roots to hit the bottom really fast and filp to flower sooner. Trust me I did multiple tests with smaller vs larger all in fabric. At the end with the larger pot I still had median mix, in the 3 gal I had all roots bearly and dirt left. In a larger 5-7 gal with airflow all around it will get bigger and stay in veg longer sometimes by as much a 3 week. Try for yourself on a 3 and 5 side by side. Do one with soil and the other with coco and see the difference. Put the coco and perlite in the bigger one.
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