Posted on

what size grow bag for marijuana

What size grow bag for marijuana

Otherwise known as terra cotta, ceramic pots offer a unique set of benefits to growers in hot climates.



Common pots used for cannabis growing


Fabric containers

When it comes to pots, your cannabis wants one thing and one thing only: a safe, healthy place for root development. Without healthy roots, your cannabis will never thrive. Roots are in charge of water retention, nutrient absorption, anchoring the plant, and also facilitate vegetative growth. All of these functions must be considered when choosing a container.

For a root system to develop and thrive, they will need the following:

What size grow bag for marijuana

As you can see, the size of your plant pot can have a large impact on how your plants grow. It is most important to make sure your roots have enough room to develop and grow, otherwise you may find that you have a stunted plant. Giving your plant more room than it needs can let it really flourish. However, you must bear in mind, whilst having too little room will definitely negatively impact your plant, having loads of room is not going to get you extra results unless other, more important factors such as light and nutrients are at optimal levels.

It is best to keep your cannabis plants in pots varying between 1.5 – 3 gallons, 3 gallons being the norm (1 gallon is 3.8 liters). If you have a lot of room in your grow space then you may even want to consider 5 gallon pots.

Choosing a plant pot is an important but often overlooked task. They come in all shapes and sizes that are all going to effect the way your plant grows in some subtle way.

What is the reasoning behind this? Well, cannabis plants grow long, winding roots; if they are restricted your roots can become “pot bound”. This simply means that there is not enough room for your roots; they cannot develop fully and thus will not be able to supply your cannabis plants the nutrients to the extent they require – leading to nutrient deficiencies.

So what is ideal pot size for a cannabis plant?

Make sure to thoroughly clean you pots before bringing them into your grow space, there may be chemical residue or other impurities left over from the shop or factory. It is also important to only put one plant in each pot, no matter what the pot size is. This will stop any need for competition between plants as well as make sure that any problems that may occur are isolated – should the soil in one pot accidentally build up toxic levels of nutrients, it will only affect one plant.

You will want to make sure that your pots are perforated (have holes in the bottom). These should rest on small dishes within your grow room. This allows for easier watering; it makes sure excess water can rest in the dish without flooding your pots – you can then remove this excess water from the dishes at will to ensure that your plants do not end up being over watered. You can also opt for putting your pots into large trays, this a more professional approach as you do not have to worry about each individual dish, but makes it harder to empty out excess water.

3 gallon pots tend to be the most commonly used pots, these offer a good balance between pot size and room to grow – your cannabis roots should have adequate enough room for a decent grow, whilst the pot doesn’t take up too much room in your grow room, allowing you to grow more plants in a restricted space.

Different pot sizes

As previously mentioned, if you have enough room, you may want to consider 5 gallon pots (or even bigger). The draw back of them is that they take up a lot of room, so it can be fairly restrictive in smaller grow areas. However, if you have the space then it can help with the production of some big yields! (light, nutrient and other factors permitting). Having a 5 gallon pot allows enough room and freedom for your roots to grow to their full potential. Cannabis tends to do most of its root growth during the vegetative stage, by encouraging huge root growth early on in this phase you set yourself up for some potentially solid yields – by having an abundance of roots towards the flowering phase your plant can take up all of the water and food it could ever need, accelerating the amount it can grow. It should be noted, large pots are an enabler; they do not directly cause better yields, but have the potential to facilitate a situation where it can happen.

The plants above are both autoflowering Flying Skunk’s (with all leaves trimmed) and have been grown under the exact same conditions. The one on the left is a 12L pot and on the right is a 4L pot. Notice the difference in size of the 2 plants.

After the water settles in a short while I’ll take it out and put it on it’s saucer. It’s always best to have the fabric pot out in the open as much as possible.

NOTE: There are ways to grow smaller plants with good yields. Search that on YouTube and you’ll see quite a few videos of people growing decent plants that are a couple feet tall. I haven’t bothered with any of those techniques because I have the room.

Let me explain further; because you’re growing indoors most likely in a spare room or your basement, you probably have height limitations. Thus, your veg cycle will be shorter because you have to control the height. Because of this you don’t need a larger pot. If you have unlimited height then a larger pot would benefit you.

For example; if you have an 8′ ceiling and you’re using hooks and hangers, your lights will hang down about 8″ from the ceiling. A modern LED light is about 8″ thick so the bottom of your light will be about 6-1/2 feet or 78″ from the floor.


I don’t like using pots outside above ground unless you can keep your eyes on them. It’s very difficult to keep track of watering a 5-7 gal fabric pot during the summer months and they can dry out so fast because of the heat and air, one missed watering could ruin your plants.

Just so you know, weed will grow in anything if you take care of it but I know what size is best for growing pot. Of course we’re talking about stealth growing indoors at home. If you have a 8′ sidewall greenhouse then you can use just about any size you want.

Once the corn started I planted my seedlings and they have grown up together getting perfect protection from the corn. Once the corn reached 4′ in height, I moved my 30 gal pots into the area. Corn is really a great way to hide a small outdoor marijuana patch.

The 5 gallon pot is the perfect size for a stealth grower when the size of the plant must be somewhat limited. It just about fits anywhere and you’ll grow great plants. Just remember that fabric pots will leak. For sure you need a saucer underneath them. To really keep it clean I put the fabric pot in a 6 gal plastic pot during watering.

You really have to be careful how close you allow your plants to get to the lights. In this scenario, if the goal is to keep your plants 18″ away from the lights (which could be too close for your strain), you have to keep your plants under 5′ (60″) in height other wise they’ll be too close and most likely will be stressed. You never know what will happen when a weed plant is stressed; from herming to stunting and everything in between.