How Many Marijuana Plants Should You Grow?

This article is the last one covering the marijuana growing basics! Even if you are an absolute beginner at gardening, our awesome guides should have given you at least some idea on where to start with your first crop. We have analyzed the basics, we have created a simple 5-step marijuana growing guide and even provided you with a shopping list for all your marijuana needs! However, a question still remains before we move into more “hands-on” tutorials: How many marijuana plants should you grow?

This seemingly simple question is actually one of the most important when it comes to setting up your marijuana garden. You might be pumped at the prospect of growing bags of weed just for you, but balance is key. To make a long story short: if you are a beginner, do not go for more than 6 plants under the same grow light. The more the plants, the bigger the possibility of something going wrong.

So is that it? Case closed? Well, not really. Let’s explore the topic a bit more by analyzing what growing a couple of plants can offer and then compare the benefits with growing a whole bunch of them! 

Growing Just a Couple of Plants

After all the pictures you’ve seen online and all the things you read about monstrous yields, the idea of growing a measly plant or two might not be what you expected. Where are the frosty dank buds and the mountains of weed that would make even Snoop Dogg look like an amateur? Can you grow that much with two plants?

Well, no. But then again, there is a whole lot of positives in a mini growing area:

• It is much easier caring for a few plants, especially if you have no experience. Think about it: Marijuana plants are living beings which need food, water, and care. The fewer the plants, the better the quality you can afford for your plants
• Your plants will bask in the sunlight: Two plants growing under a 150W HPS grow light will perform way better than four. That’s because they are exposed to more and brighter light, meaning their yields will be higher. Note however that this approach is not the most efficient and works best in smaller grow spaces
• Newsflash: Marijuana cultivation is still illegal in many places of the world! Yes, California (the 6th largest economy in the world) just legalized marijuana and yes, the “stoner stigma” is slowly disappearing among all generations (just read the polls!), but that isn’t much help if you live in a country where weed is illegal. Especially in some parts of Europe, the police might not be too keen on listening to your well-structured arguments on legalization. So, keep your grow compact and manageable!

Of course, the cautious approach still has some negative aspects, such as:

• You can’t plant more than two strains. Unless you are really set on which strain you would like to grow and commit to it, chances are you want to mix and match. So, if you are growing just two plants, you are limited to two strains maximum. What this means is that you should spend more time researching high-yielding seeds.
• Slightly longer vegetative stage. It might take a little bit more time for your plants to grow to full size and start flowering, as the canopy (= the surface that light hits) is smaller.
• You might need to train your plants to improve yields. This is not so much of a negative, as plant training is a very important part of being a grower. By growing fewer plants you will obviously get lower yields, but that doesn’t mean you can’t do anything about it. Try to experiment with training methods to enhance the production of your plants and then extrapolate! You will be impressed with what a little training can do for your plants.

The “Gung-Ho” Approach: Growing As Many Plants As You Can

This crop requires professional equipment and pretty much all of your day!

If you are lucky enough to be living in an area where recreational marijuana and/or home growing are legal, then the number of the plants is purely a matter of personal preference.

Generally, growing many marijuana plants at once comes with a bunch of positives.

• You get more bang for your buck: An 150W HPS lamp can accommodate a maximum of four plants, a 250W can fit a maximum of 8, and so on. Growing more plants under one light makes more fiscal sense. By planting four plants you get a much better gram/watt ratio, thus a better return on your initial investment.
• You get more room to play with strains: A Durban Poison, a Sour Diesel and a Jack Herer walk into a grow room… Now you can try all of these juicy strains and see which one works for you!
• Experience bigger yields faster: When growing multiple marijuana plants in a larger grow room, the vegetative stage is noticeably shorter, as the plants fill the canopy quicker.

Apart from the obvious legal implications that a larger crop might have, more plants could also mean:

• You will spend more time caring for your garden. If you are busy with work or other obligations, finding an hour each day to tend to your plants might be harder than it sounds.
• Training a lot of plants can be a b*tch. It takes some practice to learn how to train multiple plants properly without making a mess of your garden. Especially if you want to grow many strains at once, you should be aware that not all marijuana plants are created equal. Different varieties need completely different approaches and that can become a problem for beginner and experienced growers alike.

As you can see, the options pretty much cancel each other out. There is no right or wrong choice, but there are more factors to take into account when deciding the number of plants in your grow room.

So, How Many Plants Should I Grow?

Like so many other questions regarding growing, this is yet another one without a standard answer. Luckily, there are some things you can do to work the answer out yourself!

The key to getting the most out of your plants is not their number. Rather, it is the size of the surface (canopy) that is exposed to grow lights that counts. Whether you are growing one plant or ten, the goal is to increase the number of bud sites exposed to light.

Measure Your Grow Light Footprint

The “light footprint” is the total area of direct light that a plant gets during each development stage. As your plants grow, you need to readjust the light, subsequently changing the light footprint. Also, you need to bear in mind that different types of grow lights have different outputs.

Fluorescent Grow Lights

In T5 and CFL grow lights, there is no significant light footprint to speak of. All usable light is the space underneath the bulbs. Fluorescent bulbs do not emit a strong light, and therefore you should always place them within a few centimeters (inches) away from your plant (up to 30cm/1ft). Your primary concern with CFLs should be keeping them as close to your plants while making sure that they don’t touch the canopy.

HPS Grow Lights

Things are much more straightforward with HPS units. Depending on their power output, HPS grow lights will give you various light footprints.

• A 150W will cover a 60cm2 (2’x2’) area;
• A 250W will cover a 60cm2 (2’x2’) area up to a 80cm2 (2.5’x2.5’) area;
• A 400W  will cover a 90cm2 (3’x3’) area up to a 100cm2 (3.5’x3.5’) area;
• A 600W  will cover a 100cm2 (3.5’x3.5’) area up to a 120cm2 (4’x4’) area;
• A 1000W will cover a 120cm2 (4’x4’) area, up to 150cm (5’x5’);

Anything above 1000W HPS is overkill for home growing. If you want to grow cannabis as a hobby, stay below this power output.

LED Grow Lights

These light fixtures have a light footprint that varies wildly from one model to the next. Usually, manufacturers provide buyers with this information with detailed reports. Check the specifications carefully and see if they are on par with what you are looking for.

Sample Marijuana Yields Under Different Setups

If your question is not “how many plants should I grow”, but rather “what do I need to do to get X amount of yield”, we have prepared a handy little list for you:

• For an average of around 40 to 60 grams (1.5 to 2.5 oz):
  • Use 200-watt CFL lamps in a growing area that measures 1×0.5×2 m (3.5 x 1.5 x 6.5 ft.)
• For an average of around 80 to 150 grams (3.0 to 5.0 oz):
  • Use a 250-watt HPS lamp in a grow cabinet that measures 1×0.5×2 m (3.5 x 1.5 x 6.5 ft.)
• For an average of around 100 to 250 grams (4.5 to 9.0 oz):
  • Use a 400-watt HPS lamp in a grow room that measures 1x1x2.5 m (3.5 x 3.5 x 7 ft)
• For an average of around 150 to 300 grams (5.0 to 10 oz):
  • Use a 600-watt HPS lamp in a grow room that measures 1.2×1.2×2.5 m. (4 x 4 x 8 ft)
• For an average of around 250 to 500 grams (9.0 to 18 oz):
  • Use a 1000-watt HPS lamp in a grow room that measures 1.5×1.5×2.5 m. (5 x 5 x 8 ft)

So, How Many Plants Should You Grow?

Is there a limit? No there isn’t. Your imagination (and your local legislation) is the limit. Just make sure that each plant gets enough light and has an area of 30-45cm for itself. Generally, the ideal number of marijuana plants depends on the light footprint of your grow lights and the size of your grow room.

Here are some examples of how many plants fit in specific dimensions:

• 2’x2′ Space – 1-4 Plants
• 2’x4′ Space – 1-6 Plants
• 3’x3′ Space – 1-6 Plants
• 4’x4′ Space – 2-9 Plants

Bear in mind that these are rough calculations, but they are more or less on point for most growers. Make sure that you and your plants have enough room in your grow space. You will need to move things around all the time.

Some General Grower Tips

Before we wrap this article up and venture forth into the great unknowns of marijuana growing, we would like to share some additional tips with you.

Always buy feminized seeds

Generally, there is no point in buying regular seeds if you plan to grow marijuana for personal use. Almost half of your plants will end up male and you run the risk of pollination that can ruin your whole crop. Most strains are available in feminized varieties, so the chances of not finding what you need are minimal. 

Save yourself the trouble and go for feminized seeds!

Take the time to learn how to train your plants

The philosophy and practice behind plant training are like regular exercise for humans. If you take your time to do it, you will look and feel healthier! In marijuana plants, this translates to larger canopies, stronger branches and highly increased yields (up to 40% more).

Plant more seeds than you want to grow

Although it might sound counter-intuitive, beginners should plant more seeds than they actually need. That way, you can have a replacement if something goes wrong. Marijuana plants are living beings. There is every chance that something might go wrong, even if you do everything right.

Be patient

Marijuana growing is a waiting game. Let your plants grow properly before you switch to flowering. Harvest when the time is right and let your buds dry and cure properly. You will be rewarded with some of the best weed you’ve ever smoked!