Selecting The Right Container Size For Your Plants

Making sure your beauties have a safe and secure container is an important, but often overlooked task. The type of container you choose, its size, and its drainage, can all have substantial effects on the way your cannabis grows.

The Right Container Size For Your Plants

Containers come in all shapes and sizes and can be made from all sorts of materials. For many growers, it comes down to convenience, budget and availability – as cannabis can pretty much grow in anything as long as it’s clean!

Container Size

One Container For Each Cannabis Plant

Cannabis plants grow particularly long roots, and need ample room to really flourish. If you grow cannabis in a container that is too small, it can cause your plants to become root bound, leading to stunted growth.

For this reason it is very important to choose a decent container size. Standard container size varies between 4-14 liters, depending on the strain you are growing (the bigger it is, the more room it is likely to require). You can go bigger than this if you have the room, but it may not be necessary. Whilst having too little space will harm you plants, too much space isn’t going to have any positive effect unless your plant has the potential to fill it. What is important is ensuring the roots of your cannabis never run out of room. As a rule of thumb, it is best to choose the biggest containers you can practically fit in your grow area – one for each plant. That way you never have to worry about your cannabis becoming root bound.

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How Many Cannabis Plants Per Square Metre

To give you a better idea, the following list outlines the theoretical ideal amount of room for your cannabis will need, based on its age.

Note: We do not recommend working your way up through these sizes, as repotting cannabis can cause unnecessary stress on the plant. Instead, pick the size that you foresee your plants requiring in towards the end of its life cycle.

  • 0-3 weeks: root cube
  • 2-6 weeks: 10cm pot
  • 6-8 weeks: 10 litre container
  • 2-3 months: 14 litre container
  • 3-8 months: 22 litre container
  • 8-16 months: 45 litre container

Of course, these are just theoretical, with the larger sizes not always being practical, specially indoors. Cannabis doesn’t necessarily require these sizes in order to thrive, and compromise often has to be made. Outdoors it’s best to simply plant into the earth, that way there are no limitations in the first place.

Not all containers are equal

Not All Containers Are Equal

Before we get into ideal size, let us first look at construction. Plant containers can be made of pretty much anything – such as wood, plastic, metal, clay, and even plant fibre. However, just because you can have any type of construct, doesn’t mean you should. Things like clay pots will sap the moisture out of your soil, meaning you have to water more; whereas metal containers can rust, remove too much heat from the soil, and even cause contamination. Wood containers are really good for cannabis, but are often very large and expensive, so are seen as a luxury. The most common choice is plastic. Plastic containers are durable, clean, cost effective, and won’t sap the heat/water from your growing medium.

Keep Plants Separated

Keep Plants Separated

Ideally you want one container for each plant, this prevents competition amongst roots, and allows you to individually care for each of your plants. Should the soil of one container become contaminated, or over watered/fed, the rest of your crop will not suffer.

Holes or No Holes?

Holes or No Holes?

Unless you know you cannabis very well, and can gauge exactly how much water each plant needs, it is best to buy a container with holes/perforations in the bottom of it. This will allow any excess water to run out of the container, helping to decrease the chances of root rot – a problem that occurs when soil remains too wet for too long. By placing your containers on trays, you can safely collect any run off and ensure you plants don’t become waterlogged.