Best Container Sizes for Autoflowering Cannabis

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Added 08 March 2022

Autoflowering cannabis is the perfect choice for first-time growers. They are smaller and take less space than other cannabis strains like Indica, Sativa, or Hybrid. This is due to the genetics of cannabis Ruderalis, which is the foundation of autoflowering strains

And what makes autoflowering cannabis so good is that they manage to grow in various conditions, even if they are slightly unfavorable.

So, if you want to grow autoflowering cannabis, you need to consider various factors such as the growing medium, watering schedule, light systems, etc. But what most novice growers often overlook is the size of the pot. 

Yes, autoflowering cannabis will survive most conditions, but an incorrectly-sized container isn't one of them. 

Growing cannabis, whether photoperiod or autoflowers, brings a lot of excitement and anticipation, but being hasty does not help. You need to understand various factors before deciding the right size for your containers. 

This article shows you the factors you must consider for your autoflowering cannabis and how to select the right pot size to grow healthy plants with bushy buds.

Growing Autoflowering Cannabis: Factors to Consider 

Before you grab the first pot in your garden shed and throw your cannabis seedling in, you must wait and consider a few factors, which will help you figure out what size of pots to use. 

Here are a few of the factors you must consider:

The Root Zone

root zone

When it comes to growing cannabis — like many other plants — the bigger the roots, the bigger the buds. However, given the limited growth abilities of autoflowering strains, the growth root is also quite limited. As a result, the roots only grow so much before the plant starts flowering.

In the first 3-4 weeks, the roots consume nitrogen, potassium, and phosphorus for chlorophyll production and photosynthesis. Thus, the plant must have a fully grown root zone during these weeks.

In the following weeks, the roots start taking up other nutrients and minerals to support the rest of the plant growth. 

In short, no matter what type of cannabis you grow, the idea remains the same — what happens under the soil dictates how the plant grows above the soil.

So, you must consider what kind of growth you are aiming for and plan your root zone accordingly. For example, if you want a bushy, stout autoflowering plant, your root zone must be big enough to support the dense network. On the other hand, the root zone can be smaller for a regular autoflowering plant grown only for recreational use.

Drainage and Grow Medium

growing medium

Another quality that your pot must have when growing an autoflowering plant is its medium and drainage capacity. Essentially, the growing medium must promote air exchange within the root zone and have enough water retention capabilities.

This plays a crucial role in the plant's growth as adequate air and water allow the roots to absorb the nutrients and other compounds to support the plant's development. Conversely, plants suffer if there is no air or if the medium is too dry or saturated with water.

We recommend using hydroton, clay pebbles, or perlite to retain enough water in the medium since they are inert and don't affect the pH.

To promote better air exchange, you can mix the aforementioned mediums with coco coir in a 50:50 ratio. Coco holds a lot of air pockets, giving easy access to the roots.

Again, the kind of medium you use also dictates the size of the pot. If the medium does not hold enough water, you need a bigger container for adequate water supply and vice versa.

Container Type: Fabric Pots vs. Traditional Pots

fabric vs traditional pots

First, you need to determine the type of container to grow the plant. You can go with a traditional pot with drainage holes or felt pots. Note that the roots take the shape of the container and eventually end up root bound in plastic pots. It happens in any container that doesn't allow airflow.

Therefore, we recommend using felt or fabric containers that allow easy air circulation. Moreover, they are eco-friendly, reusable, and promote root pruning in the root zone.

What is root pruning? It is an automatic process that occurs in a felt pot medium. When the root hairs reach the walls of the fabric pot and come into contact with the air outside, they split and turn back into the medium. This process repeatedly occurs until there is a dense root ball within the medium. 

Root pruning encourages better plant growth as the roots don't get bound within the pot.

So, choose fabric pots if you want your plants to grow big. On the other hand, you can select a traditional container if you only want to cultivate a regular-sized autoflowering cannabis plant.



Now, coming to the biggest question: what kind of training method do you want to use? Autoflowering cannabis can be grown in various ways — you can cultivate a single plant, multiple plants in a Sea of Green (SOG), or one big plant with Screen of Green (ScrOG). 

If you are just getting started with cannabis cultivation, we recommend only growing a single plant in a small pot. If one plant with many colas suits you, you can train the plants using other techniques like LST (Low-Stress Training). Of course, you can LST multiple plants too, but methods like SOG and ScrOG helps to develop an even canopy. 

You will need various small pots if you want to raise multiple small plants to create a Sea of Green canopy. 

However, if you are a skilled grower who wants to grow a massive plant, you can use the Screen of Green method. But, you will need a bigger pot because ScrOG plants tend to take up a lot of nutrients and water, so they need a more extensive root zone.

Note that both SOG and ScrOG produce similar yields. One big difference between the two is the number of plants you cultivate. You can train the plants earlier with other training methods like Topping and Fimming to get better results. 

Choosing the Right Container Size for Autoflowering Cannabis

You can finally choose the right pot size considering all the aforementioned factors. 

Thanks to genetics, autoflowering cannabis plants grow up to 18 inches on average. However, some strains only grow to 10 inches, and some go beyond 20 inches. And they reach this height and begin blooming within a couple of months.

So, we first recommend you to read the detailed guide on your particular seed to know what to expect. Every reputable seed bank provides a detailed guide on how large and tall the plant will grow, so you can use it to figure out the initial size. 

For example, Strawberry Banana Auto grows up to 59 inches, whereas Blue Cheese Auto Indoor grows around 16 inches. So, the first strain would require a much larger grow pot, whereas the latter would only need a small grow pot.

Understanding your strain genetics will give you a general idea of how big the pot must be, but it's only the first step. You then have to consider other factors like the growing conditions, medium, pot type, etc.

There are two significant sizes that you can choose from according to the growth factors, such as the following.

Large Containers: 2.5 to 4 Gallons (10 to 15 liters)

Large containers

This is a big-sized pot for growing autoflowering cannabis, best suited for super-autoflowering strains like Strawberry Banana Auto and Gorilla Cookies Auto. So, if you want to produce massive plants, you can use these pots. 

You can also use these plants to grow an average-sized autoflowering strain paired with other growing techniques like ScrOG. Here, the larger size would help you maximize your yield by up to 20%.

In most cases, there is no need to choose a pot size bigger than five gallons — that's overkill — the plant would not utilize the medium fully, and it can be a waste of money and space. Plus, many growers think that the plant grows big with bigger containers, but that's not true, especially with autoflowers since they grow and flower depending on their own timeline. 

However, you also have to remember that the modern autoflowers released by seedbanks today are not as small as they were earlier. Some autos tend to grow gigantic. If you've grown several autoflowering plants and feel that they need a bigger pot, go ahead and accommodate them. For example, if you notice that the root ball could've done well with more space, you can plant the next batch of seeds in a 6-8 gallon pot. However, do this only if you've personally experienced it. 

Small Containers: 1.5 to 2.5 Gallons (6 to 8.5 Liters)

Small containers

For most autoflowering strains for personal use, smaller pots ranging from 1.5 to 2.5 gallons are enough, especially if the plant is not supposed to grow taller than 15 inches. 

Smaller pots, despite their size, allow the root system to develop fully without reaching root lock for regular autoflowering plants. So, they are adequate for most autoflowering strains that don't grow too tall.

Additionally, they are an excellent choice if you have limited space. They don't take up a lot of room and are portable, making them perfect for bedroom cultivators. You can even grow a cannabis plant on your study table if you find a small enough strain!

As mentioned earlier, you can still maximize yield with some techniques like LST without choosing a gigantic plant. Or you can grow multiple smaller plants with the Sea of Green method for a more significant result. 

Summary: Best Pot Sizes for Autoflowering Cannabis

Choosing the pot size is a little confusing for new growers, but you must not overlook it. If you choose the wrong container, you can affect your plant growth in various ways. 

Choose a pot that is too small, and your plant will experience root lock, which will further develop into nutrient deficiency and stunted growth. Conversely, choosing too big a pot can cause nutrient lockout along with overwatering issues. 

The process is simple — figure out your goals, growth conditions, training techniques, etc., and understand your strain's genetics. Then, choose a pot that matches the criteria.



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More autos I grow, more I see that 10 gallon pot is optimal for soil growers if they have space. Some autos strains can put even long veged photos to shade ......