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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.

FACTORS THAT DETERMINE THE NUMBER OF CANNABIS PLANTS YOU CAN GROW

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.

CANNABIS STRAIN GENETICS

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 SIZE OF YOUR INDOOR GROW

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.

THE SIZE OF YOUR POTS

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

15cm
2–3 litres: Plant height up to

25cm
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.

TRAINING YOUR PLANTS

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.

SEA OF GREEN (SOG)

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.

TOPPING AND FIMMING

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.

MAINLINING AND LOLLIPOPPING

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

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

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.

LOW-STRESS TRAINING (LST)

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.

SCREEN OF GREEN (SCROG)

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 GROW LIGHTS YOU USE

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.

GUIDELINES FOR NUMBER OF PLANTS UNDER HID LIGHTING

  • 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

LED GROW LIGHTS

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 Cannabis Plants Should I Grow? (For the Biggest/Fastest Yields)

Should you grow just one cannabis plant or many to maximize your yields? What’s the best number of plants to grow considering your grow light and the size of your grow space?

What’s the best number of plants to grow?

There are a few different schools of thought when it comes to the best number of marijuana plants to grow in an indoor setup. I’ll walk you through the benefits of growing just one plant vs the benefits of growing many, and then give you some real-life examples with specific setups. That way you get the information you need to make the best decision for your garden

One or Many Cannabis Plants: Costs vs Benefits

Growing Just 1-2 Cannabis Plants at a Time

  • Easier – Fewer plants make it easy to pay attention to each individual plant and it’s often easier to reach all the plants.
  • Much Simpler – You won’t need to compromise as much between plants with different needs.
  • Less Time Daily – Spend less time on a daily basis caring for plants (making nutrient water, watering, training plants, etc).
  • May Be Only Legal Choice – Many growers live in an area with a limit on the number of plants they can grow (for example in Canada you are only allowed to grow 4 plants at a time, and each legal US state has different growing rules). These growers don’t have a lot of choices when it comes to how many plants to grow.
  • Less Variety – You’ll only be able to grow one or two strains, instead of many strains at once.
  • Fewer (or Smaller) Harvests – Yield is based on how well you fill the grow space with plants before they start flowering. With just one or two plants, it takes extra time for each plant to fully spread out in the vegetative stage so you achieve the best yields. This results in fewer harvests a year. Alternatively, if the grow space has empty spots during the flowering stage you’ll end up with smaller yields.

Should you grow just one or two plants at a time and let them get big?

It took 8 weeks in the vegetative stage to train the plant to grow this way. Yet it was a joy to focus on just one plant and get to form a relationship with it.

In the flowering stage, the plant rewarded the effort with buds that filled the space where the plant was trained

Growing Many Cannabis Plants at a Time

  • Faster Harvests – Especially in a large grow space, several plants can fill the space faster during the vegetative stage than just one or two plants. This allows the grower to switch to the flowering stage sooner.
  • Max Yield for the Time and Electricity – A shorter grow period results in extra harvests. If you are looking to get the biggest yield in the shortest amount of time (maximizing your yield for the electricity), this is an effective strategy.
  • More Variety – With a higher number of plants, you’ll have the ability to grow a greater variety of strains at the same time.
  • More Daily Care – You will usually spend more time on a daily basis tending your plants, and it’s often more difficult to reach the plants in the back.
  • Different Plants Have Different Needs – Each plant prefers slightly different levels of nutrients, light intensity, etc. The differences can be especially stark when growing many different strains at once.
  • More Difficult to Train – Training plants to grow wide and flat results in the best yields, but it can be more difficult to train multiple plants. Some plants grow much taller/faster than others, and you have work around all the other plants. To simplify things, some growers avoid any training when growing many plants at once.
  • May Be Illegal Where You Live – It may be against the law to grow a large number of plants even if growing is legal where you live.

Should you grow many plants so they fill your grow space faster?

It only took 6 weeks for those plants to completely fill up this grow space. Imagine how long it would have taken for one plant to grow this big!

No Matter How Many Plants You Grow…

  • Similar Yields Per Square Foot – Cannabis yields are based mostly on the size/shape of the canopy in relation to your grow light, not the number of plants. Filling the total surface area of plants under the light with bud sites is what matters, and it doesn’t really matter if you use one plant or many to fill the space before flipping to the flowering stage.

That means even if you can only grow a few plants at a time, you can still get the same yields in your grow space as someone who can grow more plants! It just might take a little bit longer in the vegetative stage.

It doesn’t matter whether this canopy was created by one plant or many. However you got here, your yields will be about the same as long as everything else is equal!

Growing Many Plants Shortens the Vegetative Stage But Doesn’t Necessarily Increase Yields

When it comes to getting the best yields as fast as possible, you will often have better luck growing several plants than just one or two. This is because it takes several plants less time to completely fill up a space than it would take one plant to fill up that same space.

However, time might not be the main concern. Many growers don’t mind an extra few weeks in the vegetative stage if it makes the growing process easier and more fun.

But in the end, the actual yields will be about the same as long as the space does get filled. Given the same total number of colas and size of plants, it won’t matter much if you have one plant or twenty as far as yields are concerned.

What’s the “Optimal” Number of Cannabis Plants?

If you can legally grow as many marijuana plants as you want and are willing to put in the extra time and effort to grow as many plants as necessary, what’s the best number of plants to grow?

Each plant should get plenty of direct light and at least a foot or two of space to itself

The optimum number of plants depends mostly the size of the area under the grow light. A plant generally should get at least a foot of space to itself to really be able to grow and spread out, and it’s often better to give plants a little more space, especially if you have powerful grow lights like HPS or LEDs!

Suggestions for Example Grow Spaces

2’x2′ Space – 1-4 Plants

2’x4′ Space – 1-6 Plants

3’x3′ Space – 1-6 Plants

4’x4′ Space – 2-9 Plants

These suggestions definitely aren’t set in stone, but they serve to give you general starting guidelines. It is possible to grow more plants in these spaces successfully, but with more plants, you will often start running into difficulty being able to reach the plants in the back and care for them properly. Sometimes it’s more of a pain than it’s worth.

These two plants fill this entire 4’x4′ space, but you could get the same amount of canopy coverage with many smaller plants. It’s up to you to decide how you want to fill your space

Keep in Mind! Your yields are limited by the size of your grow light, not the number of plants. Light is like food for your plants and has a direct correlation with yields. The more plants you grow, the less each individual plant will get as far as light. Think of your grow light like a pie, with each additional plant getting a smaller slice to eat every day.

It’s tempting to grow a lot of plants, but you don’t want to spread your light out too thin! If you grow too many plants you might get less than an ounce per plant, and your buds will be airy and light!

Your yields are ultimately limited by the size of your grow light, regardless of how many plants you grow.

All of the following grows took place in a 2’x4’x6′ tent and produced a comparable amount of weed

3 plants (5-gallon pots)

4 plants (3-gallon pots)

7 plants (2-gallon pots)

It can be hard deciding what number of plants to grow in your space, but ultimately the best thing you can do is to pick a number and dive right in to growing. I believe in listening to your gut. When in doubt, always start with more plants than you need so you have the option of ditching any plant that doesn’t germinate, grows poorly, or ends up being a male or hermie.

Always start with more plants than you need, just in case! But remember, you may have to throw some of them away…

Each grower has a different style, and as you get more experience, you’ll be able to dial in your grow to what’s best for you and your setup.

Many growers find it more relaxing and enjoyable to grow just a few plants (or even just one). On the other hand, growing many plants at a time produces more strains, more often. The right choice depends on you and your needs.

So unfortunately I can’t give you a “best” number to end all numbers, but I hope you now have a better idea of how many plants to grow in your space!

Beginner Shopping List (What You Need to Start Growing)

How Many Cannabis Plants Should I Grow? (For the Biggest/Fastest Yields) Should you grow just one cannabis plant or many to maximize your yields? What’s the best number of plants to grow