FastBuds seedbank #1 with 10426 diaries and a rating of Growdiaries 8.8/10 on GrowDiaries
Growdiaries 8.8/10 with 10426 diaries on GrowDiaries

Best Pot Size for Autoflowering Seeds

Which pot size is best for growing from seed until harvest, what to consider, as well as our top tips on choosing just the right size.
02 June 2022
8 min read
Best Pot Size for Autoflowering Seeds

  • 1. What to consider before planting
  • 1. a. 1-4 large-sized plants (10-15 liters / 2.65-4 gallons)
  • 1. b. 6-10 smaller plants (6.5-8.5 liters / 1.72-2.25 gallons)
  • 1. c. Screen of green (10-15 liters / 2.65-4 gallons)
  • 1. d. Using custom soil beds
  • 2. It's all about the roots
  • 3. The importance of drainage when growing autos
  • 4. Which pots are best?
  • 5. Plant directly in the pot you plan to harvest from
  • 6. Top tips on choosing the best size pot for cannabis
  • 7. In conclusion

Once you have purchased your Fast Buds seeds and have germinated them, full of excitement and anticipation, next you will need to decide on the pot size, medium, and location. In this article, we explain the best pot size for cultivating autoflowering Cannabis from seed until harvest, which pots are best, the importance of drainage, including our top tips.


Sebastian Good talks about the best Pot and Container Size for Autoflowering Cannabis.

1. What To Consider Before Planting

Before you just pick any pot size and throw your seedling in there, it is a good idea to consider a few variables that may help sway your decision. Thanks to the diversity of autoflowering Cannabis and how well they adapt to all climates, the options to grow one large plant, use SCROG, grow several smaller plants packed closely together, or simply plant directly into the ground are available. Each has their own benefits and are better explained below, so what's the best size pot for growing weed?

1-4 Large-Sized Plants (10-15 liters / 2.65-4 gallons)

If you are limited to plant count, or grow space then deciding to grow 1-4 large-sized plants will warrant the need for big pots such as 10-15L. The bigger the pots then taller the final plant should finish once harvest time comes around. 


Best pot size for autoflowers: large-sized plants

Optimal pot size for large plants in a limited space.

There is no need to grow an autoflowering seed in a huge pot size (bigger than 15L) because much of the medium will not be fully utilized as if using a 10L pot for example.

6-10 Smaller Plants (6.5-8.5 liters / 1.72-2.25 gallons)

Cultivating autoflowering Cannabis in a Sea of Green setup, using the right cultivar can reward a grower with great returns. An excellent way to use up all of the growing space and work with homogenous and uniform cultivars. Smaller pots of 6.5-8.5L will be fine.


Best pot size for autoflowers: smaller plants

Optimal pot size for the SOG setup.

You may have smaller-sized plants resulting in lower yields, however, it will make up for that with the high number of plants.

Screen Of Green (10-15 liters / 2.65-4 gallons)

For the more adventurous grower skilled in-plant training, using a screen to grow your auto-flowering plants through has advantages when increasing yields. However, the screen may limit the mobility of your plants as they will be built into a net frame.


Best pot size for autoflowers: scrog

Best pot size for the SCROG method.

Using Custom Soil Beds

Another alternative if you prefer not to use mobile plant pots, is to plant directly into the ground. Preferably an organic soil bed that has been specially created for cultivating autoflowering Cannabis and is teaming with microbial life.

2. It's All About The Roots

In the gardening world there is a saying that the bigger the roots then the bigger the fruits, although when discussing autoflowering Cannabis, the root growth is somewhat limited. It is during the first 3-4 weeks that auto-flowering plants will use up Nitrogen, Phosphorus, and Potassium to aid the development of photosynthesis, chlorophyll production, and anchoring of a well-established root zone into the medium.


Best pot size for autoflowers: roots

Make sure to leave enough space for the rooting of your plant.

It is the root zone that is responsible for the uptake and distribution of nutrients, minerals, and the distribution of growth hormone to the rest of the plant pathways. How deep and wide the root zone is will make a huge difference in what is occurring above the soil.

3. The Importance of Drainage When Growing Autos

There are a number of qualities your pots should have, and the most basic yet often overlooked is drainage. How well your plants can drain, promoting air exchange through the root zone, and allowing the medium to dry out, will play a big role in the growth and development of the cultivar. Hydroton is small clay balls that are a bright orange color. Traditionally used in landscape gardening, and recirculating hydroponic systems, these nutrient-free and totally inert expanded clay balls work wonders to allow water to freely pass through.


Best pot size for autoflowers: drainage

It is essential to provide your plantwith an appropriate drainage system.

Paired with coco coir at a 50/50 ratio or used to line the bottom 1-2 inches of your pots, hydroton will increase the number of air pockets present, encouraging roots to expand outwards in search of new oxygen-rich pockets. Inadequate drainage will cause the growing medium to become waterlogged, over time reducing the oxygen around the roots. Not only will roots suffer when this occurs, but nutrient uptake and transpiration will also temporarily cease until the preferred conditions are met.

4. Which Pots Are Best?

Fabric pots are far more beneficial than traditional plastic pots with holes in the bottom. Not only are felt pots more environmentally friendly, but they can also be easily washed, re-used, and most importantly will promote root pruning. In the same way, topping a Cannabis plant will cause the two crown shoots to grow in replacement of the one that was topped, root hairs will do the same. This, of course, occurs in the dark, warm environment that exists in the medium when root hairs travel to the side of the pots. As they come into contact with the outside air, they will form two root hairs and then turn back until the same process takes place repeatedly.


Best pot size for autoflowers: best pots

Fabric pots allow for a better air circulation in the roots.

  • Root pruning will produce a far superior plant in comparison to one grown in plastic pots.
  • The concern for root-bound plants that will become stunted is eliminated with felt pots.
  • They can be made at home to your custom size and easily washed and cleaned between use.

Just remember that the proper air pot size for autoflower is the same as any other pot size but the difference is that when growing in air pots or fabric pots, the roots get pruned by air naturally, as they would in nature;  This means that it's harder for your plants to get rootbound and due to the roots getting pruned slowly and gradually, it won't affect your yields or strunt growth. Obviously, they're more expensive than regular plastic pots so you will have to see if they're worth it in your case but a lot of growers have compared them side to side and the plant in the air or fabric pot grows slightly better, but as always, it's up to you to experiment and reach your own conclusions.

5. Plant Directly in the Pot You Plan to Harvest From

Autoflowering cannabis strains are fantastic. They offer huge advantages in many ways over photoperiod cannabis plants - smaller overall size for extra discreetness, much simpler lighting demands meaning they can be grown all year round outdoors and easier perpetual harvest routines, higher resilience against pests and diseases, smaller feeding demands, and all still with bumper yields in shorter periods.

But, they do come with one pretty obvious downside (depending on how you like to grow). They really can’t handle stress or training in the same way as photoperiod plants. This is due to the fact that thanks to the inbuilt genetic timer that all autos carry, they simply do not have the time to recover before the flowering stage of growth begins. Any sort of stress or training that your plants undergo causes a pause in the vegetative growth while the plant recovers. This pause could last anywhere from about 4 days to a week and a half, depending on the overall health of the plant and how heavy the stress imparted upon it is.

One of the huge upsides of autoflowering cannabis plants is the short lifecycle. Depending on the strain (and to some respect, the phenotype - variances within a strain) they usually take less than 10 weeks from seed to harvest. And with today’s genetics, they still offer plus 25% THC and huge yields. Amazing, right? But, this means that autos usually have less than a month of vegetative growth before they automatically switch over to the flowering period. Stressing or training a plant should always be done during the vegetative growth stage so you do not stunt the flowering growth. This is fine with photoperiod plants, as you can simply extend the veg growth period by keeping the lights at 18/6. Not the case with autos.

To combat this, you need to give your auto girls the best chance of hitting their full potential. Every time you transplant a cannabis plant you put her under stress, which will definitely stunt the growth for at least a few days. To counter this all you have to do is plant directly into the pot you plan to harvest from. This gives your autos the best chance at reaching their full potential. Now, this is a generalization. For sure, there are some autoflowering strains that can deal better with training and stress. If you love experimenting with different training techniques and pot sizings then we suggest that you stick with the larger autos in our collection. Sativa-dominant strains usually run a little longer than their Indica sisters, and this means you have a little more time to play. 

6. Top Tips On Choosing The Best Size Pot For Cannabis

1. Decide in advance based on your space what format of growing, works to your advantage. If 1-4 large-sized plants are more practical, or if a Sea of Green has more advantages.


2. No matter if you are choosing plastic or felt, make sure the pots have been totally cleaned and sterilized to the best of your ability. Especially if re-using the pot for a second or third run.


3. Lots of smaller-sized plants will yield the same amount as fewer large-sized plants, so do not be tricked into thinking a Sea of Green is not advantageous or worthwhile.


4. Do not use more than 15 liters (4 gallons) of medium per auto-flowering plant. It is best to work with sizes 6.5-15 liter (1.7-4 gallons) depending on the chosen style of growing, the cultivar, and the climate you are living in.


5. If you have a sewing machine, ordering a large roll of thick felt will allow you to customize your own pots, making them the exact size and shape you prefer.


6. Adding a bottom layer of hydroton clay balls at the base of your pots will improve drainage and the exchange of oxygen around the root zone.

7. In Conclusion

There's no such thing as a best size pot or perfect pot size to grow cannabis because it depends on your preferences and growing setup, there is a balance between growing in a pot size that is too small and growing into something so large that the medium, nutrients, and vital grow space are not fully being taken advantage of.


Zkittlez Auto
5 out of 5
Just an easy to grow, solid packed buds. A heavy feeder and can be a bit prone to light burn at the end but otherwise perfection!
Verified customer
Reviewed 21 November 2020

Fabric pots will increase root mass, prevent air pruning, and help save the planet at the same time. Learning which autoflowering cultivars adapt better to which scenario takes time and experience and will help give you the upper hand when it comes to efficiency and productivity. For smaller-sized pots we advise Zkittles Auto, Gelato Auto, and Stardawg Auto. When it comes to cultivating in large-sized pots, we recommend Orange Sherbet Auto, Wedding Cheesecake Auto and Six Shooter Auto.

02 June 2022