For a root system to develop and thrive, they will need the following:
Common pots used for cannabis growing.
Otherwise known as terra cotta, ceramic pots offer a unique set of benefits to growers in hot climates.
Traditional plastic containers.
Check out these additional resources on soil and planting:
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.
Garden centers and grow supply chains offer different pots that vary by material composition, shape, size, and perforation style.
A relatively new innovation in container gardening, roots in fabric pots grow to the outer edges and attempt to bypass the porous fabric wall. Instead, they are cut back, allowing new growth to occur. This process, called “air pruning,” results in a denser root composition which promotes healthy growth and development.
Standard plastic containers are a popular option for growers operating on a budget. These pots are inexpensive, but still provide the essentials for your plants.
This post was originally published on March 13, 2018. It was most recently updated on June 29, 2020.
Standard plant container with saucer.
When choosing the size of your containers, you must think about the final size of your plant. Bigger plants will need bigger containers, while smaller plants grow best in a relatively small container. You need to match the size of your plant with the size of your container.
Summary How to water cannabis seedlings or clones in a too-big container.
A general guide is to have up to 2 gallons per 12″ of height. This isn’t perfect, since plants often grow differently, and some plants are short and wide instead of tall, but this is a good rule of thumb.
Managing and adjusting pH is crucial to success in a soilless growing medium.
Soilless (coco coir, perlite, vermiculite, etc)
As mentioned earlier, some growers start their marijuana plants in their final container, which is usually larger than a 1-gallon pot. Starting in a big container isn’t as simple as starting with a small container, and can cause slower growth at first, but here’s you can take to get a seedling to grow quickly in a large container.
Happy cannabis roots want…
If you’re using a Smart Pot (fabric pot) or any container that lets in oxygen from the sides, you’ll get faster growth than a hard-sided container. However you will also need to water your plants more often since the soil will dry out more quickly.
12+ gallon container.
Need to water less often with hempy buckets, which is a great advantage when growing larger plants that drink a lot.
Since growing medium dries out from the sides, air pots make it difficult to overwater your plants, but that also means you will end up watering more often.
Here’s a breakdown of those different container options…
When seedlings or clones are started in a large container, it can be difficult to get enough air to the roots until the plant is bigger and drinking a lot. Thisis because when the potting mix gets soaked, the seedling roots just won’t be able to drink it fast enough, and the roots will end up sitting in stagnant water with very little acces to oxygen. The growing medium has to dry out on it’s own, which can take a while, and your plant will be droopy and overwatered until the roots start getting access to air again.
What do marijuana roots want?
When starting your cannabis grow with properly amended and composted soil, pH isn’t as important for you to manage. Instead of managing pH, you need to manage and care for the bacteria and microorganisms in the soil. In a proper composted soil setup, the microorganisms deliver nutrients to your roots in the right form. They become the “middle man.”
Many growers start their plants in a solo cup or a 1-gallon pot.
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.
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.
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.
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.
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.
So what is ideal pot size for a cannabis plant?
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.
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.
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.