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Choosing the right pot size for your cannabis plants
Choosing a pot for your plants is an essential but often-overlooked task. There are pots of all sizes and shapes, and they affect the way your plants grow subtly.
The best cannabis pot size: small to medium-sized pots (6 to 12 litres)
It is best to grow your cannabis plants in pots that are between 6 and 12 litres in size. Smaller-sized pots of 6.5 to 8.5 litres are ideal for many training methods, such as cultivating autoflowers in a Sea of Green setup. It’s a great way to utilize all of the grow space and work with homogeneous, even crops. You can have smaller sized plants which will obviously lead to lower yields, but the greater quantity of plants will offset this.
This size container – or indeed larger ones – also works well for the Screen of Green (ScroG) method which is suitable for an intrepid grower who is proficient at plant training. It involves a screen to support your plants and can dramatically increase yields. Nonetheless, the screen may slightly restrict the mobility of the plants as they are entwined in a mesh frame.
12-litre pots are the most commonly used pots, and they offer a good balance between pot size and space to grow: your roots should have enough space for proper growth and the pots do not take up too much room in the grow space, allowing you to grow more plants in a small space. If you are limited in the number of plants or grow space, deciding to grow 1-4 tall plants will justify the need for medium-sized pots of 10-15 litres.
Even larger pots
If you have a lot of room in your grow room, you might even consider having 20-litre pots. The larger the pots, the more finished the final plant should be at harvest time.
The downside is that they take up a lot of space and therefore, can be restrictive in more limited grow spaces. However, if you have enough space, they can help produce some big yields! (if light, nutrients and other factors allow).
Having 20-litre pots gives enough space and freedom for your roots to reach their full potential. Cannabis does most of its root development during the vegetative growth phase, by encouraging good root growth early in this phase, you are setting yourself up to have good potential yields. Because the plant has a lot of roots during the flowering stage, your plant can absorb all the water and nutrients it might need, which increases the quantities produced. It should be noted that large pots are only facilitators: they do not directly cause an increase in yields, but they can facilitate them if the other conditions are met.
Things to consider
Besides the pot size there are a few things to keep in mind:
You need to make sure that all of your pots have drainage holes – you can easily make these yourself if they don’t come supplied. They should rest on a small plate or dish in your grow room. This allows for easy watering: excess water can settle in the saucer without flooding your pots, and you can flush out this excess water whenever you want so your plants don’t get overwatered. You can also choose to arrange your jars in large trays, this is a more professional approach as you no longer have to worry about each individual dish, but then it is more difficult to remove excess water.
Make sure to clean your pots thoroughly before bringing them into your grow space as they might contain chemical residue or other impurities from the store or plant. It is also important to only place one plant in each pot, regardless of the size of the pot. This will eliminate any competition between plants and help isolate potential problems. If the soil in a pot accidentally accumulates toxic levels of nutrients, then only one plant will be affected.
Hydrogenated are small balls of clay that are bright orange. Traditionally used in landscaped gardens and hydroponic setups, these nutrient-free and completely inert expanded clay balls are amazing at allowing water to pass freely. Combined with coconut coir in a 50/50 ratio or simply placed at the bottom of your tubs, Hydroton grow rocks will increase the number of air pockets present, and encourage the roots to spread outwards in search of new ones.
Inadequate drainage will result in waterlogging of the growing medium, over time, reducing the oxygen around the roots. Not only will the roots suffer, but transpiration and nutrient uptake and will also temporarily stop until the ideal conditions are met.
As you can see, the size of your pots can have a massive impact on how your plants grow. In the world of horticulture, it is said that the bigger the roots, the bigger the fruit; although when it comes to autoflowering cannabis, root growth is more limited. It is during the first month that autoflowering plants need phosphorus, nitrogen and potassium to facilitate the development of photosynthesis, the production of chlorophyll and the anchoring of a root zone well-established in the culture medium.
It is vital to make sure that the roots have enough room to grow or develop; otherwise, you will end up with a slow-growing or stunted plant. Giving more space than necessary for a plant allows it to really thrive. However, it would be best if you remembered that while having insufficient space affects the plant negatively, giving it a lot of freedom will not bring additional results unless other essential factors such as light and nutrients are at optimal levels.
After all, the root zone is responsible for the absorption and distribution of minerals, nutrients, and the growth hormone auxin to other pathways in the plant. The depth and width of the root zone make a massive difference to what goes above the ground.
Tips for choosing the size of the pot
Decide beforehand, based on your grow space, which grow format is right for you, and if 1-4 large plants will be easier to manage, or if a sea of green setup is more advantageous.
It doesn’t matter whether you choose plastic or a biodegradable substance; make sure the tubs have been thoroughly cleaned and sanitised to the best of your ability, particularly if you are reusing the pot for a second time.
Many small plants will perform the same as fewer large plants, so don’t fool yourself into thinking that a sea of green is not beneficial or useful.