What Is the Ideal Grow Room Size Per Plant?

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If you’re planning to grow cannabis indoors, you’re probably faced with the common question of how to choose the optimal grow room size. Thankfully, there are quick calculations that make this decision easy for indoor gardeners.

If you’re trying to establish space for a serious grow, you can use these calculations to decide how much space you’ll need for your grow tent. If you’re working with an existing space, you’ll be able to figure out how many cannabis plants you can reasonably accommodate.

Factors That Influence Grow Room Size

When setting up a grow tent, there are more factors to consider than just the number of plants. There are other important variables, such as:

  • The grow method. There are numerous methods for growing cannabis. For instance, the Sea of Green (SOG) method can accommodate a lot of plants in a tight space (since plants only require about 1 square foot of space and not much vertical space). Other methods, like the SCReen of Green (SCROG) method, require more space per plant.
  • The size of the containers. Cannabis containers commonly measure 1.5 to 3 gallons, although some growers prefer to use pots measuring 5 gallons or larger. The size of your containers will greatly influence the number of marijuana plants you can accommodate for your grow.
  • Lighting conditions. Your typical LED grow lights will need to draw about 30 to 40 watts for every square inch of growing space. So if you have a 2 x 2 space, you’ll need 60 to 80 watts. For a 10 x 10 space, you’ll need 300 to 400 watts. You’ll need to factor in your lighting needs when considering your total grow room capacity.
    • Pro tip: You can use reflectors to enhance your wattage output, potentially reducing your total lighting requirements.

You’ll also need to account for any other essential items that can occupy space in your grow tent or room, such as fans, ducts, and filters. A well-designed tent will maximize space by keeping these items largely out of the way, but they can still creep into your square footage. So it’s important to know exactly how much space you’re working with.

High-Stress and Low-Stress Growing Methods

Your growing method is arguably the most important variable when determining the number of plants for your grow space. Grow methods can be either low-stress or high-stress.

  • Low Stress Training. Most growers will use a Low Stress Training (LST) method which manipulates the shape and orientation of each plant to encourage optimal yields.
  • High Stress Training. Although less common among beginning and intermediate growers, High Stress Training (HST) methods are also available. HST methods seek to place excess stress on crops to encourage higher yields. It’s not easy, but when done properly, it can reap massive rewards.

The following are the five most common growing methods:

  • Sea of Green (SOG): With this low-stress method, a large number of small plants are huddled together in a compacted space. The yield per mature plant tends to be lower (since there’s not as much room to grow and breathe), but the higher number of plants tends to offset this issue.
  • SCReen of Green (SCROG): With this low-stress method, special screens are placed over the plants to encourage horizontal rather than vertical growth (hence the name). The plants are also topped in most cases, a process whereby the main stalk is cut to promote a wider, bushier plant. Naturally, this requires more plant spacing than the SOG method. This method allows for higher yields with fewer plants, and it also accommodates larger plants than the SOG method.
  • Topping: Trimming the top growth can be done on its own without the aforementioned screen. Another LST method, it’s known for encouraging bushier plants, though you have to be diligent about trimming your plants in such a way that all of the growth tips are equally exposed to the available light. The SOG method makes this easier, but topping on its own requires less space.
  • Fimming: Fimming is another LST method that’s similar to topping, but it specifically involves cutting off around 75% of the tip of each plant. The name literally means “F*ck, I missed” on account of how sloppy the technique can appear. In reality, fimming is a highly effective pruning technique that forces the plant to create more lateral branches, thereby ensuring optimal light penetration.
  • Supercropping: The most common HST method is supercropping. The technique involves bending the tips of branches, thereby forcing the hormones to lower branches. This results in a more robust harvest. Because the tips are bent at a 90-degree angle and should never touch, the containers require a bit of space between them.

Ideal Square Footage for Different Growing Methods

Once you know your preferred growing method, you can get a pretty good idea of your ideal grow room size per plant. Use the following table to estimate your approximate needs:


Growing Method  Avg. Square Footage Per Plant 
Sea of Green (SOG) 1 sq. ft. per plant
SCReen of Green (SCROG) 4 sq. ft. per plant
Topping 1.5 sq. ft. per plant
Fimming 1.5 sq. ft. per plant
Super cropping 2 sq. ft. per plant

So using the standards above, let’s assume you have an 8 x 8 grow tent. With one of these units, you could grow 8 plants using the SOG method, 2 plants using the SCROG method, 5 plants using the topping or fimming method, and 4 plants using the super cropping method. Again, this assumes that you use the optimal container size and spacing for your chosen method.

Other Factors Influencing Grow Room Size Per Plant

It’s not enough to estimate the square footage when putting a grow room together. While a larger tent is good for larger yields, you also have to look beyond your basic grow tent size and maximize your use of space. For example:

  • The shape of your grow area is important. If you want to grow four or six plants, experts commonly recommend a rectangular tent shape (like a 4 x 8 size tent, for instance). This allows you to maximize your perimeter space and achieve optimal horizontal growth without crowding. Rectangular tents work best in general, but they can be increasingly difficult to manage with higher numbers of plants. If you don’t have the space for a rectangular tent, a square will do the trick.
  • The size of your pots will also impact your yields and the amount of labor required. Small pots are generally recommended for the SOG method, while medium containers work well for most other methods. A larger 5-gallon pot will maximize your yields but occupy more space, so you have to consider what’s most important to you.
  • Autoflowers need as much space as other plants. Some people believe that, because autoflowers are smaller, they’re more compact. But while it’s true that they don’t grow as tall, they can still reach considerable width.

Choosing a Grow Tent for Your Space

Unless you have the budget or resources to build a complete grow room from scratch (complete with the appropriate ducts, ventilation, lighting, and humidity control — humidification and dehumidification — equipment, your best bet is to invest in a grow tent that offers the space you need.

  • Shop trusted brands and retailers. When you buy from an industry leader like Trim Buddies or GrowAce, you can find a reliable tent with all the necessary accessories—in just the size you need.
  • Make sure your tent comes with the essentials: a reflective inner-lining, vents to promote airflow, frames and rods to support your grow lights and other essentials, and any necessary ductwork that you might need. Some of the fancier tents will even include lights, advanced filtration systems, and other extras.
  • Choose a tent that has the square footage you need.
    • For a single plant, a 2 x 2 may be sufficient.
    • For two plants, a 2 x 4 or 4 x 4 tent should do the trick.
    • For six to eight plants, go with a 4 x 8 tent.
    • For 10 plants, go with a 5 x 10 tent.
    • When you get beyond 10 plants, you might need to use multiple tents, particularly if you’re working in a limited-sized space.

Figuring out the square footage is the easiest part. The important thing is to ensure that all of your plants have ample space to flourish and grow. So choose your indoor grow space carefully. It will make all the difference for your yields.

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