Theories on pot sizing?

I'm looking to repot my seedlings... I started them in 5" square pots, the plants vary from 4-6 inches in height now and I am just starting to see roots come out the bottom of the pots. My question is this- is it better to repot in a slightly larger pot more often ( like to an 8" then 10", ect) or do I jump right to the 6 gallon pot now? I only have 5 plants, space in my room/ under lights really isn't an issue.
im curious as to what method most of you use, and do you have a particular reason for doing so. I have heard mixed things on each approach.

Hey buddy,

It's recommended to gradually build up in pot size as the plant develops to promote a denser rootball, I usually pot my seedlings up into a 3L pot, then a 5L, then a 9L and finally a 12L but I have gone straight from 3L to 12L with no overall difference whatsoever in final yield, but tend to gradually pot up anyway to save space in my veg tent.

You could put half your seedlings in 6 gal pots and gradually pot the others up, then you will have first hand experience....the best kind

Thanks for the quick response GuitarisGr8!
i guess I was worried about shocking the plants each repot, so figured less moves was better. The idea of the denser rootball makes sense. I thought it was space issue for the more seasoned growers which doesn't really apply to me since I only have a few plants.

Every time you re-pot your adding new soil.
Older soil, you run the risk of salt build up in the soil.

The other Idea of re-potting more often is that the plant grows roots first then starts to grow the shoot.
Your supposed to get faster shoot growth because don't have a lot of space to grow roots.
The plant knows how much soil it's in. When the roots hit a surface, and turn around they send a protein signal telling the shoot
"This is all the space we have". The shoot starts to grow again, but it only grows to the size of what ever container you have it in.
Big Container Big Plant - Little container little plant. You'll never see a 5 foot tall plant growing in a cup of soil for this reason.

Good Luck on Your Grow.


I usually transplant 2x's. solo-cup to 1 gallon grow bag, and then to 3 gallon grow bag.
You can grow a 4' - 5' plant in 3 gallons of soil. also depends on how many watts your lights are.

Shawangunk Skunk said:

Thanks for the quick response GuitarisGr8!
i guess I was worried about shocking the plants each repot, so figured less moves was better. The idea of the denser rootball makes sense. I thought it was space issue for the more seasoned growers which doesn't really apply to me since I only have a few plants.

Click to expand...

I used to have the same worries, but once you don't make a mess of the transplant they are happy in their new homes after a nights sleep.
Best of luck.

Thanks for a great explanation Topfuel. So if I understand you correctly the roots grow and max out in the pot size first, then energy is focused on above ground growth until maxed to pot size, enlarge pot size and the process repeats. If I were to go strait to largest pot size it would be quite a while until I saw above ground growth as roots would max out first? In theory anyway.

Yes... if you go to the biggest size pot right away the plants will concentrate on the roots. That's one of the reasons you should NEVER transplant right before you flower.

You will see growth on top after transplanting, it just slows way down for a week or two until the roots fill in.

Sent from Northern Colorado.

guitarisgr8 said:

Hey buddy,

It's recommended to gradually build up in pot size as the plant develops to promote a denser rootball, I usually pot my seedlings up into a 3L pot, then a 5L, then a 9L and finally a 12L but I have gone straight from 3L to 12L with no overall difference whatsoever in final yield, but tend to gradually pot up anyway to save space in my veg tent.

You could put half your seedlings in 6 gal pots and gradually pot the others up, then you will have first hand experience....the best kind

Click to expand...

In my opinion this is good advice if you're growing a long term plant but with our plants which we expect to have done in 4 - 5 months I find this is counterproductive... Your plant will grow faster if you don't force it's roots to wrap in on themselves for the entire vegetative stage. Take your small starter cup and go straight into a 5 - 7 gallon pot. Your vegetative times will be reduced and your main stalks will be larger than incrementally sizing up your containers. I've been doing this forever with far better results. Veg 2 - 4 weeks in a small container and then go straight to a large one. I just watched a video recently on here from medicropper and it appears he recently has found out the same thing. he no longer goes incrementally larger pots and goes from starter cup straight to large pot. Trust me your stalks will 2-3 inches thick at 12 - 18" in height..

Merlin34 said:

Yes... if you go to the biggest size pot right away the plants will concentrate on the roots. That's one of the reasons you should NEVER transplant right before you flower.

You will see growth on top after transplanting, it just slows way down for a week or two until the roots fill in.

Sent from Northern Colorado.

Click to expand...

This is true. Everyone should go with small ass pots for the first 30 days then go directly to a 7 gallon for another 30 days and the stalk will be huge which means the buds will be huge. When I reach the height I want I go directly into a 7 or 10 gallon pot. I cut the lowest branches and bury the plant a little so it's a bit shorter when transplanting. The roots go nuts and the main stalk expands, the plant fills out as well.

Thanks SuperTiger, that's a lot of great information! I wish I read your post earlier as I just got done transplanting from 4" into 3.5L (8") pots. As I mentioned, this is my first grow so I am learning a ton. I started my seeds in these 4 pots thinking the less transplanting the better off I would be. Next go around I will start in the smaller beer cups and try your suggestion above.

does this work with cloning too? I thought I would try that once these plants got a little bigger. But still have some research to do on cloning.

here are the girls repotted, at almost 5 weeks. I just switched my nutes from MG 18-18-21 to 30-10-10.

The way to get the biggest plants is to start small like you did then go big. I go straight to 10 gal containers and my plants get HUGE I have a skywalker plant in veg already 3 foot tall.

metal or glass containers are not the best I would try to get either plastic(cheapest) fabric pots(really good) or airpots(really good).

I grow clones and seedlings in a 3" pot then go to 1 gal. then to 5s 2 weeks before flowering.

Thanks Yodaweed, the plants are all I n plastic pots. The two pots on the right are sitting in a stainless tray to prevent water from leaking all over.

General rule is that a 3-gallon potwill support the life cycle of a plant for 3 months. Do you really plan on keeping a plant for 6 months? As you noticed, the root system grows out first to support the plant. You can tell about when the roots reach the pot edge as those roots grow about the same rate as your widest leaves. When the leaves reach the pot edge it is time to consider transplanting. When the roots reach their limit is when the plant goes into inch-a-day vegetative growth. TP now if you want a bigger, taller plant. Flower now for a shorter, bushier plant. Smaller the pot the sooner she goes into veg. BigSteve.

Many companies and people like to overcomplicate shit. You need some basic things to grow good quality bud.

1) Good soil, like a roots organic premix.
2) Good lighting, Like 400 watts HPS which will effectively cover a 2'x3' - 3'x4' area (preferably a 600w HPS)
3) RO water or distilled water. Stay away from tapwater.
4) Nutes. I use all organic Espoma Soil Acidifier, Espoma Garden Lyme, Espoma Dried Blood, Espoma Bone Meal, Espoma Garden-Tone, Espoma Kelp Meal, Espoma Potash, Espoma Single Phosphate, molasses, worm castings, guano, tea etc..
5) Mold/Pest control = Lady Bug Juice and Organicide
6) Time and focus

I start out with solo cup and depending on if it's seed or clone, I pot to a 2-gallon within 7-10 days from sprout or cloning. My 2 gallon fabric pot is my final container and I get just as good results as I did with 7-10 gallon plastic containers. I do a 4-6 week veg time depending on the plant. (For indoor anyway)

Your growing conditions also contribute a lot to the size of pot needed, ie; outdoor vs in. Outdoors the larger pots 7-10 gallon can still give you 8-12 foot monsters!

I used fabric pots (aurora) my first grow. Never again. They may be great for the air root pruning aspect but if you ever need to move your plants around, lift them up and check weight, those fabric pots suck. You are almost guaranteed to mildly upset the root system every time you move a fabric pot which means you lose days, shock your plants.. I guess if you're going to set your pot down and never touch it again go for the fabric pot but I recommend using plastic square pots.

supertiger said:

I used fabric pots (aurora) my first grow. Never again. They may be great for the air root pruning aspect but if you ever need to move your plants around, lift them up and check weight, those fabric pots suck. You are almost guaranteed to mildly upset the root system every time you move a fabric pot which means you lose days, shock your plants.. I guess if you're going to set your pot down and never touch it again go for the fabric pot but I recommend using plastic square pots.

Click to expand...

I actually move my fabric pots daily. I also had the foresight to put them on saucers.

tusseltussel said:

I grow clones and seedlings in a 3" pot then go to 1 gal. then to 5s 2 weeks before flowering.

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I wanted to add that I veg for 60 days. If I was only going with a 30 day veg I would probably start in a 3 inch pot and transplant into 3 or probably 5gal.
Also I am using 7s now