Why pot size matters in cannabis cultivation

The best pot size for cannabis cultivators

As plants grow, their pots stay uniform, so the right pot for cannabis seedlings may not work once they’ve reached the flowering phase. But how do you know for sure? Outside of data from substrate sensors, your own labor could be a strong indicator.

Let’s say your potted plants are in a growth period that requires giving them an additional irrigation shot during the dark period at night. Adding this nighttime feeding, or P3, isn’t ideal because it means the plants aren’t getting enough water during the day to support them at night  – most likely because they’re too big for their pots.

Roots need room to grow, so when a plant has outgrown its container, its ability to retain nutrients declines. This has to do with volumetric water content (VWC). Dry backs mark the decrease in VWC percentages between the last irrigation event of a given day and the first irrigation event of the next day. As cultivators steer their plants toward particular vegetative or generative outcomes, growing plants in the wrong-sized pots could have a negative impact on drybacks and ultimately yields.

Plus, your team will likely need to perform more tasks (like adding a P3 shot) to keep the plants healthy.

Sometimes bigger is better, but it depends

In the above scenario, a larger pot size would be better for the plants and could eliminate the need for a P3. That’s one less chore, and less water used for irrigation – a resource economy that producers love. But a bigger pot won't always be the solution – going smaller may make more sense in facilities dealing with space limitations.

Picking a pot size isn't a one-and-done decision. Choosing containers that accommodate what’s happening in the root zone at all phases can set you and your plants up for success.

For more on the importance of choosing the right pot size, check out this segment from Office Hours Episode 44.

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