Home Growing Cannabis? What container size and material is best for growing weed?

Growing marijuana at home? If you have any additional questions or would like to see more research in future harvests, shoot us a message on instagram: Montana_Canna_Co

Cannabis plants in different pot sizes and materials

Well this was a surprise to me even though I’ve been growing hundreds of cannabis plants commercially for over 3 years. Having researched the ‘best pot for pot’ multiple times before starting my business, this was one of the 1,000 preparation items already crossed off the list. However, after multiple harvests, any farmer gets backlogged and in my case, I was being bottlenecked on multiple fronts:

  1. Expanding the farm = more pots needed.
  2. Getting sick of cleaning pots in real time = more pots purchased.
  3. Contemplating downsizing the pot size to save $$ on soil = smaller pots purchased.
  4. Looking for uniformity and handles = different pots purchased.

So 3 years deep I’ve got a modest collection of different containers:

  • 5 Gallon buckets with holes drilled in them for airflow (heavy, takes a LOT of soil to fill up, dirt flows out during watering)
  • 5 Gallon fabric pots with handles (very nice but difficult to clean)
  • 3 Gallon plastic pots with air holes (no handles and lots of dirt flows out when watering)
  • 3 Gallon fabric pots with handles (very nice but difficult to clean)
  • 1 Gallon fabric pots (insanely small)
  • 1 Gallon plastic pots (insanely small)

I decided that enough evidence was amassed that hypothesized we could grow just as big of plants in small amounts of soil as we could in large ones. I’d taken part in solo cup grow challenges and some of the finished plants were enormous. If those plants could grow out of a solo cup, then why was I spending hundreds and thousands of dollars on soil every harvest and spending an entire day filling up 5 gallon pots? I’d also seen competitors growing very nice plants in 1 gallon pots. Time for a trial.

I chose 3 strains out of the 7 that would be growing in our May — July harvest and decided that I’d separate them into all the available pots and space out randomly so there would be a control over light/temp/wind and overall environmental consistency. With the room set, all I had to do was feed/water/defoliate and watch the magic happen.

We water about 2/3 gallon per day on automatic fertigation systems and I was expecting to have trouble dialing in the feed with the different pots. I only have feed control over a whole zone/table so there’s no adjusting for over/under water on an individual basis so we did our best to find the middle point and let it ride.

On harvest day, I took the wet weight of all the plants. Then we dissected the root balls. And finally, after a week and half of drying, we stripped the flower and weighed the un-trimmed bud from each plant.

Cannabis harvest weighs per pot size and material

My research had identified fabric as being the best grow material due to the breathability of it. Supposedly the roots would get more air and be more efficient in their duties. Additionally, the soil would dry out faster, allowing for increase feed frequency which is a huge factor in plant size and speed of growth. Plastic containers tended to encourage more root growth as they encompassed the entire internal shape of the container doing their job… looking for food etc. Fabric pots tend to ‘air prune’ the roots and leave them contained in the middle of the soil. What I found on harvest was quite the opposite. The plastic containers seemed to do much better on plant weight as well as final product weight than the fabric containers.

My assumption here is that there was simply more root mass in the plastic containers and with the single watering per day, the larger root mass was able to take up more nutrients, water and essentially do more work than the air pruned roots in the fabric. Unfortunately, I have a sneaking suspicion that if I had been watering less per day but more frequently, the less efficient roots would have been able to perform better and we may have seen different results. But alas, this experiment is done and the results are clear. For our process on our farm, the 3 gallon plastic pots did much better with the exception of the Butterscotch strain.

Montana Cannabis Company - Flathead Valley, MT

Next we are testing multiple LED Grow Lights: Gavita 1700e, Phantom Bio, Mars Hydro FC-e8000, and the Flexstar.



Thanks for reading.