How Many Plants in a Grow Tent / Grow Room?
Getting a good yield is about growing the right number and right size plants.
Don’t cram too many plants into your tent. You won’t get a bigger yield by overcrowding plants. Instead, you’re likely to stunt growth and dent your yield.
Often you can get just as much yield - or even more - from fewer, bigger plants.
So how many plants should you grow in a tent or room?
The exact number of plants depends on many factors, including:
- The size of your plants
- Your growing system (the shape of pots, space between pots, size of pots, etc)
- Your grow lights
- The rest of the equipment in your tent
However, the main thing to do is leave enough space around plants for lateral growth. You don’t just want plants to grow tall – you want them to be big and bushy.
As a rough guide, you’re best off aiming for 1 – 4 plants per square metre.
Some people allow their plants to become too big during vegetative growth, and fail to leave room for any growth in flowering. By the end of the veg period, plants should be around half their final size. With that in mind, keep the veg period relatively short if you can only accommodate small plants.
If you want to let them develop but haven’t got space for the extra growth, you’re going to need a bigger room or tent.
You can grow more smaller plants, or fewer larger plants. Here’s what we recommend for our main tent sizes:
|Number of Plants|
|75cm x 75cm||1 – 2 plants|
|100cm x 100cm||1 – 3 plants|
|120cm x 120cm (XL)||1 – 4 plants|
|100cm x 150cm||1 – 4 plants|
|120cm x 240cm (XXL)||2 – 8 plants|
|150cm x 150cm||2 – 6 plants|
|150cm x 200cm||2 – 8 plants|
|150cm x 300cm||4 – 12 plants|
|100cm x 300cm||3 – 9 plants|
|200cm x 200cm||4 – 12 plants|
|200cm x 300cm||4 – 16 plants|
|240cm x 240cm||4 – 16 plants|
|360cm x 240cm||6 – 24 plants|
|300cm x 300cm||6 – 24 plants|
|600cm x 300cm||12 – 48 plants|
If your tent size isn’t on this list, you just need to do a bit of maths:
Work out how much floor space you have.
Multiply your tent's L x W (length x width)
e.g. a 3m x 3m x 2m tent has 3 x 3 = 9 sq.m of floor space.
(floor space) x (number of plants you want to grow per sq.m)
(e.g. a 9 sq.m x 3 plants = 18 pot system)
Remember – we recommend 1 – 4 plants per sq. m.
Maximise Floor Space
There are a few different ways to maximise the available floor space you have:
1. Use Expando Tent Supports
If space is tight in your tent, try Expando Tent Supports.
They keep your tent canvas taut and enlarge your growing space by up to 30cm (depending on the tightness of your canvas). That’s 7.5cm per wall.
They fit tents that:
- Are 1m or bigger
- Have 16mm - 28mm poles
- Have gaps between tent poles of 1m - 1.5m
2. Use a taller tent & low-profile system
Some growers find they are unable to allow plants to grow to their full potential because as plants grow, they get too close to their light source (which they're unable to move due to lack of headroom). When this happens, they cut their vegetative cycle short and flip to flowering earlier.
To prevent this from happening, consider using a taller 2.2m or 2.4m grow tent (you may need a more powerful light as a result) and/or low-profile system. Doing this will allow you to keep a safe gap between your grow lights and canopy.
If you find that your plants have filled out your floor space, prune plants so that they can grow taller without growing too big and bushy for your tent.
Ultimately, you just have more space in your tent for plant mass.
Picking a system
Remember to pick your growing system carefully for your tent. It’s not just about matching the number of pots to the number of plants you want to grow – you need to make sure the system physically fits into your tent.
Modular systems – like RhizoSystems - tend to be quite flexible. You have more choice over how you connect and where you position pots. For instance, you can have fewer long lines, or more shorter lines. This means you can match your system to the shape of your tent.
Other systems are a bit more rigid. For instance, NFT systems are just the size and shape that they are. You don’t have the flexibility to change your layout, unless using multiples in a larger tent.
What Size Pots?
Once you know how many plants you’re going to grow, if you’re using a pot-based system, you need to pick the right number of pots and the right size pots.
Generally, you should use 50 – 60L of growing media per 1 – 1.2m2 of space in your tent.
50 – 60L will fill:
- 6 x 8L pots
- 4 x 12L pots
- 2 x 30L pots
- 1 x 56L pot
So if you decided you wanted to grow 4 plants in a 120cm x 120cm area, you would need 4 x 12L pots.
We always recommend using RhizoPots, which are made from fabric. They allow air to contact root tips and ‘air prune’ roots. When this happens, rather than simply growing forwards, towards the edge of pots, roots start branching and producing secondary and tertiary roots.
Overall, you end up with a denser root network that's spread more evenly through the media, giving plants access to the nutrients and water in the central space. You also get more root tips for extra uptake.