how many cannabis plants can you fit

How Many Cannabis Plants Can You Grow Per Square Metre?

Congratulations on committing to cannabis cultivation. Now you need to settle upon the right number of cannabis plants to grow. We’ve got practical advice you can use to determine how many plants to fit per square metre.

Factors that determine how many plants you can grow per square metre.

  • 1. Factors that determine the number of cannabis plants you can grow
  • 2. Cannabis strain genetics
  • 3. The size of your indoor grow
  • 4. The size of your pots
  • 5. Training your plants
  • 5.a. Sea of green (SOG)
  • 5.b. Topping and fimming
  • 5.c. Mainlining and lollipopping
  • 5.d. Low-stress training (LST)
  • 5.e. Screen of green (ScrOG)
  • 6. The grow lights you use
  • 6.a. Guidelines for number of plants under HID lighting
  • 6.b. LED grow lights
  • 1. Factors that determine the number of cannabis plants you can grow
  • 2. Cannabis strain genetics
  • 3. The size of your indoor grow
  • 4. The size of your pots
  • 5. Training your plants
  • 5.a. Sea of green (SOG)
  • 5.b. Topping and fimming
  • 5.c. Mainlining and lollipopping
  • 5.d. Low-stress training (LST)
  • 5.e. Screen of green (ScrOG)
  • 6. The grow lights you use
  • 6.a. Guidelines for number of plants under HID lighting
  • 6.b. LED grow lights

Before you get started with your indoor grow operation, you need to have a plan. Among the things you need to think about is how many cannabis plants you can feasibly fit in your grow space.


From the available space in your tent to the size of your pots and the type of lights you’re using, several factors influence the number of plants you can reasonably fit per square metre.


The first thing to consider is the type of cannabis you’re growing—the strain genetics. Sativas tend to grow tall, while indicas are stocky and bushier. Autoflowers grow particularly short, with some varieties reaching only 50–60cm.

Even those without significant spatial limitations tend to choose shorter cannabis varieties when growing indoors. After all, you are responsible for providing illumination, so you need to account for the space taken up by your grow lights. Moreover, if you’re growing different strains and some end up being much taller than others, this can deprive smaller specimens of light, resulting in stretching and reduced final yields.

If you don’t plan on training your plants, consider growing the same type of strain, or two strains with very similar heights, to avoid running into issues with spacing and lighting. Of course, the smaller and more compact your plants, the more you can fit per square metre. It’s up to you to decide if you’d rather crop several small autoflowers or just one or two ultra-vigorous hybrids.


The dimensions of your growing area will largely dictate how many plants you can grow per square metre, and in general. If you’re like most home growers, you’ll likely be using a grow tent set up in a suitable location in your home.

Grow tents are available in many different sizes, from small 50 × 50cm tents to large ones that could fill half your room. The right size depends on what strain(s) you’re growing, how large your indoor growing space is, and what type of grow you are going for (heavy training, leaving plants to develop as is, etc.).

As an example, if you just want to grow a single untrained photoperiod indica plant, a 1 × 1m tent should be sufficient. As you add more plants, you’ll need to scale up accordingly. But again, don’t just account for the eventual size of the plants themselves, but also lighting, ventilation, and other equipment.


Depending on the diameter of your pots, several can fit into one square metre. But the size of your containers doesn’t just impact how many plants can fit per square metre, but also how big the plants will get overall. Said differently: The larger your pots, the bigger your plants will get.

Recommendations for pot sizes:

½ litre: Seedlings and young plants up to

2–3 litres: Plant height up to

5 litres: Plant height up to 60cm
11 litres and more: Average plant height (check strain description)

For the average indoor grow, you can fit nine 11-litre pots per square metre.

Use rectangular planting pots to fully take advantage of your available growing area. With round planting pots, you’ll be wasting valuable space.

See our planting pot calculator to find the optimal pot size for your cannabis plants.

  • 21L – 1 plants m²
  • 18L – 2 plants m²
  • 15L – 5 plants m²
  • 11L – 9 plants m²
  • 5L – 18 plants m²
  • 3L – 25 plants m²

The environmentally friendly RQS fabric pot, complete with proprietary “Aqua Breathe” geotextile layer, lets your plant’s roots breathe for optimal growth.

The environmentally friendly RQS fabric pot, complete with proprietary “Aqua Breathe” geotextile layer, lets your plant’s roots breathe for optimal growth.


With plant training techniques, you can keep the number of cannabis plants to a minimum while maxing out their potential. Each of these training techniques is designed to optimise space and increase yields.


4–16 plants per square metre
Outcomes: Fast yield, keeps plants short, easy to perform, comparatively smaller yields per plant

The sea of green method (SOG) is all about getting the most out of your available floor space. It is a good way to achieve a consistent outcome with photoperiod plants, clones, and autoflowers. This technique is fast and profit-yielding.

In a SOG, plants only get 1–2 weeks of vegetative growth before they are forced to switch to flowering. No pruning or training is needed. As the plants don’t have time to branch out, the result is many short plants with short main colas.

Under a 400W HPS light, you can fit 4–16 plants per m² in 5–12l containers. An optimal SOG grow can deliver multiple 500g/m² harvests per year.


2 large/5–10 small plants per square metre
Outcomes: Simple to perform, keeps height in check, boosts yield, prolongs growth phase

Topping and fimming are high-stress training methods. By cutting off or pinching the main growing tip, you break the apical dominance of a plant so it develops multiple main colas instead of just one. This naturally results in bushier growth and causes plants to stop growing in their characteristic Christmas tree shape.

Any high-stress training technique that involves damaging your plants (like both topping and fimming) slows down growth and extends the vegetative phase. If you’re pruning, topping, and/or fimming, allow your plants to recover and expect a later harvest date. Don’t overdo it; top or FIM 2–3 times per growing season.


1 large/2–4 small plants per square metre
Outcomes: Challenging to perform, consistent results, options for beginners and more advanced growers

Mainlining and lollipopping are two plant training techniques that promote the growth of large buds at the ends of branches.


Mainlining is a mix of topping, LST, lollipopping, and ScrOG. Plants are topped at the third node, with all the lower branches cut. This causes new growth to develop equally from one central hub, and plants are often topped a second or third time to develop multiple colas and an even canopy. This can fill up your grow space significantly depending on how many colas and the size of your pots, so keep in mind you may be able to fit fewer mainlined plants per square metre.


Lollipopping is complementary but can be done on untrained plants too. All branches—including the main stem—are trimmed of unnecessary growth, leaving only the main bud and side branches with large buds. Just as with mainlining, the plant now directs energy toward the large buds.


2–4 large/4–6 medium plants per square metre
Outcomes: Suitable for autoflowers (no topping needed), best for beginners, requires no major recovery time

LST is a beginner-friendly training technique. You’re essentially just bending and tying down stems during vegetative growth to manipulate plants into growing horizontally. LST can be combined with other techniques, such as ScrOG. It is often done together with topping to break apical dominance, but it can also be performed without topping on autoflowers. Between 2–4 plants trained with LST can effectively fill 1m².


1–2 large plants/4 medium-sized plants per square metre
Outcomes: Best yield per square metre, flexible with how many plants you want to use, for advanced growers only

A ScrOG is the best way to utilise a single square metre of growing space. In this advanced training method, the screen is a grid-like mesh (chicken wire, netting, etc.) through which shoots of developing cannabis plants are woven to control growth. Growers usually start weaving their ScrOG during the vegetative phase and end it before the third week of bloom.

A ScrOG keeps only the main colas under the light so the plant’s energy goes toward bud production. Top your plants early to get more branches, then proceed to train them in multiple directions through the screen. This way, you can get the maximum yield from your available growing space.

You can choose how many plants/pots you use for a ScrOG. You could fill your space with only one monstrous plant in a large 20l pot, but you could also grow several smaller plants, such as four medium-sized plants each in a 10l pot.


The last factor that determines how many plants you can fit into each square metre of your grow space is the type, and intensity, of your grow lights. This becomes ever-more clear when you realise that grow lights don’t spread light evenly across the entire area.

The greatest light intensity (and thus the fattest buds) is right underneath the light, then decreases significantly toward the sides. This could make growing fewer plants more sensible, as you’ll probably be sacrificing yield to poor light spread if you cram in too many. There’s no point in depriving any of your ladies.

If you’re growing weed with HID (high-intensity discharge) lights, a simple formula can give you a rough estimate for the recommended number of plants. Divide the wattage of your light by 75 and round up the fractions.


  • 150W HID ÷ 75 = 2 plants
  • 250W HID ÷ 75 = 3.3 or 4 plants
  • 400W HID ÷ 75 = 5.3 or 6 plants
  • 600W HID ÷ 75 = 8 plants
  • 1000W HID ÷ 75 = 13.3 or 14 plants

When using CFLs, divide by 150. For example, using a 400W CFL: 400W ÷ 150 = 2.6 or 3 plants


Modern LEDs output the same power as HPS using only 60% of the energy. Therefore, they cover the same space in less wattage. A good 250W LED is equal to a 400W HPS, which can cover around 5–6 plants. By comparison, a high-powered 1200W LED should be able to cover around 8–9 plants.

However, keep in mind that wattage is only one value to consider when it comes to determining the power of your LEDs, as many other variables—including the type of LED—impact their effectiveness too.

When using LEDs, it is best to consult the manufacturer for the recommended number of plants to grow and the optimal distance from your lights to your plants’ canopy. Reputable manufacturers usually make this type of information available.

  • PRO TIP: If uncertain about how many plants you want to grow, it’s always better to keep it “safe” with fewer plants. Two large but happy plants with fat buds will ultimately be better than a tent full of small, light-starved cannabis that will only yield mini buds. In addition to that, you’ll also save on seeds.

Not sure how much marijuana to grow? This blog will help you figure out the right number of cannabis plants to fit in each square metre of your grow space.

How Many Plants to Maximize Grow Space?

If you’re about to start growing cannabis, you have a decision to make: How many plants do you want to grow?

This is one of the most common questions I hear from new growers, and it’s great if you’re asking this question because it’s actually pretty important.

If you grow too many or too few plants, you may not get the yields you want, and it can possibly take longer than needed until you get to harvest. It’s a little bit of a balancing act of finding the right amount of plants to achieve your goals.

The short answer is that for one grow light, you should plan on growing 1-8 plants. If you grow more than 8 plants under a single grow light, chances are you’re hurting your yields by not giving each plant enough space to thrive.

Don’t grow more than 8 plants under a single grow light

In the following pic, there are too many plants to grow all the way to harvest under a single grow light – each plant won’t get enough light and space to produce a significant amount of dense bud. The small pot size needed to fit this many plants in a small space will also eventually stunt each plant even if they did get enough space and light. This grower would likely get bigger yields by growing fewer plants in bigger pots.

There are several factors that make a difference when it comes to how many cannabis plants you should grow including the size of your space and what grow lights you’re using. I’ll explain each factor so you can grow the perfect number of plants for your setup to maximize yields and harvest as soon as possible!

Factors to Consider

Size of grow space

Type/Size of containers

Ease of growing

Desired timeline (How soon do you want to harvest?)

Size of Grow Space

The total size of your grow space affects the number of containers you can fit in your grow space. If you have small containers you will physically be able to fit more in your grow space than if you were using big containers. If you’re growing with extra big containers (for example a DWC reservoir) you may only be able to fit one or two plants in your grow space.

Because the DWC reservoir is large, there really isn’t enough room for another container in this grow tent

Type/Size of Containers

Going along with the size of your space, the size of your containers affects how big your plants will get. Smaller containers can support smaller plants, but if you want big plants you want big containers. Which size container? (full guide)

The max number of plants is determined by how many plant containers you can physically fit in your grow space

You will likely end up growing less plants than this max, but you won’t be able to grow more! Once you know what size container(s) you plan to use, you’ll be able to figure out the upper limit of how many can physically fit in your grow space.

As a general rule, for hand-watered plants if your final (desired) plant size is…

2-3 gallon container

3-5 gallon container

5-7 gallon container

6-10 gallon container

8-10+ gallon container

Too-small pots can stunt plants and cause symptoms that look like nutrient deficiencies. Learn how to transplant plants to a bigger pot.

The space around each plant container needs to be big enough to support the desired plant size! Keep in mind that each plant is likely going to be bigger than the width of its container, and needs enough room to spread out!

Think about how big you want each plant to get, and leave enough room around each container to support the plant you want.

Grow Light Part 1 – Figure Out Your Light Footprint

The grow light you use determines your total available light coverage (how much space can actually support plants). If you have a small grow light, it will only have a small amount of coverage even in a big grow space. You can only grow vibrant plants within a grow light’s “light footprint” – where the plant is getting direct light.

Therefore the size of the light indirectly determines how much space you can use to grow plants. If desired, you can actually measure your light footprint directly by using a cheap lux meter. Or use the following general guidelines…

For CFLs & Other Fluorescents (like the T5), the light footprint includes only the space directly under the bulbs, as the light (usable by plants) from fluorescent lighting does not travel much further than a few inches. All parts of the plant should be within a foot of a bulb, otherwise they’ll be outside the light footprint. Therefore the total footprint depends on how you configure your CFLs or fluorescents.

CFLs or fluorescent grow lights should be kept just a few inches away from your plants

For MH/HPS , your light footprint is as follows:

  • 150W – covers 2′ x 2′ (0.6m x 0.6m) area
  • 250W – covers 2′ x 2′ (0.6m x 0.6m) area up to 2.5′ x 2.5′ (0.8m x 0.8m)
  • 400W – covers 3′ x 3′ (0.9m x 0.9m) area up to 3.5′ x 3.5′ (1m x 1m)
  • 600W – covers 3.5′ x 3.5′ (1m x 1m) area up to 4′ x 4′ (1.2m x 1.2m)
  • 1000W – covers 4′ x 4′ (1.2m x 1.2m) area up to 5′ x 5′ (1.5m x 1.5m)

A 150W HPS grow light can cover up to a 2’x2′ area, so all the plants in this picture are getting good light levels. However, any plants outside that main area would be starved for light. You can actually see the corners of this tent are in shadow.

For LEDs , the light footprint is different depending on the model, and you can get this information from the manufacturer. Feel free to check out a short list of some cannabis-tested LED grow lights which includes their light footprint information.

The Kind “K3 L600” LED grow light (like the one pictured below) has a light footprint of 3’x4′. That means any plants growing inside that area under the lamp will be fine, but plants outside that footprint won’t be getting enough light.

Grow Light Part 2 – Make Sure There’s Enough Total Light Power for Each Plant

When it comes to the size of the grow light vs how many plants, you never want to give a plant less than 75W worth of light per plant for HPS/LED, and 150W per plant for CFL/T5. A plant that receives less light than this likely will never get big enough to produce a significant amount of bud, or buds will be airy. So make sure to consider the size of your light so you don’t grow more plants than your grow light can handle!

HPS/LED: At least 75W per plant

CFL/T5: At least 150W per plant

As an example, if you had a 400W HPS grow light, you use the formula this way: Take 400÷75=5.3. That means you probably shouldn’t grow more than 5 plants under a 400W HPS grow light.

If you had 400W worth of CFLs, you would take 400÷150=2.6. That means you really shouldn’t grow more than 2-3 plants under that many CFLs.

It’s important to keep in mind that these figures are bare minimums! For example, in my current setup each plant I grow gets 250W to itself, while Sirius’ plants get 300W per plant.

Desired Ease of Growing

The number of plants you grow affects the overall ease of growing. Ultimately, more plants generally means more work and effort. Plants often need to be watered and trained individually, plus if you have more than one row of plants it can be really difficult to tend to the plants that are all the way in the back.

Growing just one plant at a time is the easiest, but you end up only harvesting one strain. When you are growing lot of plants of different strains at once there’s more of a chance that some of the plants will grow very differently from the others, which can be frustrating. If one plant is 3x the height of all the others, it becomes much more difficult to give every plant what it needs!

If you choose different strains, you may be surprised at how differently they grow in the exact same environment!

When it comes to desired ease of growing, opt for fewer plants for an easier grow, and opt for more plants if you really want extra strains and/or are willing to spend the extra time it takes to watch over and tend to many plants at once.

Desired Timeline + Yields (How soon and how much do you want to harvest?)

The amount of yield you can achieve with a good grow is determined less by the number of plants and more by your strain, skill and grow light (learn more about what determines your yields). Generally for any strain you will get about the same total yields from one or many plants, just as long as you fill up the space under the grow light.

But the timeline (how long it takes until harvest) is partially determined by how many plants you choose to grow, and this indirectly affects your yields.

As an example, if you’re growing in a 3’x3′ space, it might take 8 weeks in the vegetative stage to get just one plant to completely fill up that space. A single plant needs enough time to grow big enough to support all the buds you want to harvest. If you switched to flowering earlier than that, it would ultimately hurt your yields because you’d be wasting some of the space under the light.

This single plant needed almost 8 weeks in the vegetative stage to get big enough to fill in most of the grow tent

But if you were growing 2 plants in the same setup, each one would only need to grow half the size in the vegetative stage to achieve the same amount of coverage under the light. This is because a single seedling has less leaf mass and simply can’t use as much light as two seedlings. Less wasted light = more total growth. If you were growing 4 plants, each one only need to grow 1/4 the size to achieve the same coverage in the vegetative stage.

This fact can be used to shorten your veg stage because whether you’re growing one plant or many, once you’ve achieved that coverage in the vegetative stage you’ll end up getting similar yields at harvest. In other words, with more plants you may need less time to fill up your available growing space, which can save you a few weeks of veg time, leading to a quicker harvest!

Together, these 4 plants have created a canopy that is a similar shape, length and width as the single plant above. This means the yields will be similar (if the light and strain are the same). However, they only needed 6 weeks in the vegetative stage to achieve this size (2 weeks less veg time than the single plant above) so were able to switch the flowering stage sooner.

Ultimately, growing more plants (up to a point) allows you to have a shorter vegetative stage since your grow space will fill up much more quickly. And a shorter vegetative stage ends up saving you electricity and time! That being said, for some growers a few extra weeks of veg time is worth the fact that you have to spend less time tending your plants every day.

So in some ways when it comes to timelines/yields and number of plants, it’s a matter of deciding how much personal time you want to put in to your grow on a regular basis vs how much time you are willing to wait to get to harvest. If growing several strains and getting to harvest as quickly as possible is most important to you, opt for more plants (up to 8 under each individual grow light). If you want a grow that’s easier and less time-consuming, opt for fewer plants.

Start with More Plants Than You Plan To Grow

If it’s your first grow (and honestly in general) it’s a good idea to start with more plants than you need. This lets you choose the best plants of the bunch and not be stuck with any weaklings that just aren’t growing as well as the others. Plus you never know when a seed won’t germinate or come with some other problem like a bad mutation.

This grower started with 6 plants even though they only planned on growing out two. This way if there’s a weakling or one of the seeds doesn’t germinate, it doesn’t affect your grow!

Start with Feminized Seeds

With non-feminized seeds, about half of your plants will end up being male (which need to be thrown away) and that can seriously mess with your plant numbers. To make things worse, due to the random nature of genetics sometimes you can end up with something like 5 males and 1 female out of six seeds (just as you can get 5 females and 1 male). This can make it hard to plan for the number of plants, because on average you would expect to get 3 females from 6 non-feminized seeds.

To make things a LOT easier for you as far as plant numbers, choose to start with feminized seeds (available for most strains). With feminized seeds, all your plants will end up being bud-bearing female plants, which means you get to keep all your plants.

Get feminized seeds from a trusted breeder

Maximize Yields by Filling Up Your Grow Space via Plant Training

The best yields indoors are achieved by using plant training to force cannabis plants to grow flat and wide. This is true for just about every indoor growing setup that uses grow lights. Plant training lets you fill up the entire space under your grow light with an even canopy of colas, and this can increase yields up to 40% compared to not training at all. Plus it’s free! If you don’t want to learn any new techniques but still want all the benefits, check out our page on no-technique plant training.

Example of the manifolding technique in action, which is a specific way to train the plant in the early vegetative stage to create multiple big colas instead of just one.

Ultimately, no matter what technique you use (or even if you use our no-technique plant training) your goal is to to grow a plant with many main buds like this.

When a plant is not trained, it only produces one main bud per plant. You don’t want this! It will reduce your overall yields indoors because only the single bud closest to the light will get big and fat. You want many main buds to get the most from your grow lights, and the best way to accomplish that is with plant training!

Now that you know how many cannabis plants you want to grow, time to start growing!

Rule #1: Don’t grow more than 8 plants under a single grow light. Rule #2: Ask yourself these 6 questions to figure out the best # of plants for your grow space!