How Many Autoflowers Can I Grow In A Square Meter?
There are several things that help control the size of an autoflower, things like genetics, lights, and pot size make it possible to grow up to 6 plants per 1m2.
Almost all cannabis consumers that want to start cultivating their own cannabis want to fulfill their needs without having to spend too much. To do that, you have to make the most out of your grow space.
There are a number of things that can help you achieve that without having to spend more in another grow setup.
1. What Determines Plant Size In Nature?
When growing in nature, there’s nothing to limit a plant’s size. As they’re not growing in closed space, cannabis plants grown outdoors can grow even more than 3m tall.
That, of course, doesn’t apply to indoor growers.
Indoor growers have a limited amount of growing space, lights, nutrients, and medium. This can be seen as a bad thing, but this also gives us the ability to have complete control of our plant, being able to determine how tall, bushy, and even how much buds it will produce.
To do that, we adjust the type of light and size of the pot, we can also apply plant training and pruning to adapt the plants to what we have available.
2. What Determines Plant Size Indoors?
There are a couple of main factors that will determine the size our plant will grow. All of them can be adjusted to fit your preferences and can be adjusted according to your grow space and genetics you’re growing.
As you may know, Sativas grow tall and thin and Indicas grow short and bushy. This is one of the main factors that will affect how your plant grows. Even though nowadays it’s hard to find a pure Sativa or Indica, the hybrids most growers cultivate is a mix of pure Indica and Sativa genetics, and depending on the hybrid (it can be Sativa or Indica-dominant) it will grow shorter or taller.
A great example of a hybrid strain is our Orange Sherbet Auto which grows tall and bushy, showing characteristics of both Indica and Sativa lineage.
This is the first thing we should have in mind, a Sativa-dominant hybrid can grow more than 2m tall if no training is applied, while an Indica hybrid can reach up to 1.4m tall. So, if you’re looking to grow Sativa-dominant strains, you won’t be able to fit as much in your grow tent as if you were growing Indica-dominant plants.
Pot size is another very important factor. The amount the roots grow underneath will reflect directly in the size of your plant, so if you grow in a 5L pot your plant will be smaller than if you grow in a 10L pot.
Even if there’s a difference in the size of Sativa and Indica-dominant strains, pot size will decrease their overall size, as they won’t have space for the roots to grow.
For autoflowers, we recommend not going too big when choosing the pot size. Usually, an autoflower in an 11L pot will grow to its full height, as where an autoflower in a 5L pot will grow of medium height and in a 3L will grow small.
If you don’t have space issues, we recommend going with 11-12L pots so your plants can develop to their fullest.
Light coverage and intensity will also influence, not only in the size but also in the amount of resin and density of buds. When you grow too many plants in a small space, some will throw shade over others and the ones left underneath will not be able to develop properly.
That’s why you need to know the size of your grow space before buying the grow lights, this will ensure you get good coverage that can satisfy all your plants.
There are numerous plant training techniques, even though the methods vary, all of them have the same goal: adjust your plant to the growing space.
For autoflowers we recommend using low stress training (LST) techniques or using the Sea of Green (SOG) method to make the most out of your grow room.
3. How To Calculate The Area Of My Growing Space
Calculating the area of your growing space is fairly simple. To do this, we need a measuring tape to measure the length and width of our growing space. If we are planning to grow in a grow tent, we can find this information in the manual, but if it isn’t available, it is fairly simple to measure it.
So for example, if after measuring the length of our growing space is 1m and the width is 1m, we multiply both to get the total area, so: 1×1 = 1m 2 .
This applies to any size, even if our growing space is not a perfect square.
Another example is: length = 2 and width = 3, we would have an area of 2 x 3 = 6 m 2
This is extremely helpful because based on the area of our growing space we can calculate the potency of the light we will need and the number of plants we can fit in it.
Tip: If you’re measuring in cm, divide the result by 100 to have the area size in m 2 . For example: 200 x 400 = 800cm 2 , 800cm 2 ÷ 100 = 8m 2 .
4. Calculate Number Of Plants Based On Pot Size
For these examples, we will use a growing space of 1m 2 but you can do the math with your space’s measurements and you will have the same result.
Calculating exactly how many plants we can fit in our growing space can be difficult, this is a general guide and may vary depending on your growing environment.
Pots come in different shapes and sizes, and depending on the size, you will be able to fit several in your grow space. There’s no general rule but depending on the size of the pot you choose, you will limit the size of your roots, which will have a direct impact on the plant’s size.
Usually, we use the following table as a guide:
|Pot Size||Number Of Plants Per m 2||Plant Size|
|11L||9||Full plant height|
|15L||5||Full plant height|
|18L||2||Full plant height|
|21L||1||Full plant height|
We can calculate the number of plants by multiplying the number of plants by the area of our growing space. So let’s say, our growing space has a width of 2m and a length of 3m, (2 x 3 = 6) the area of our growing space would be 6m 2 .
So, based on the table, we can have 5 plants on 15L pots in 1m 2 , so we multiply the number of plants by the area: 5 plants x 6m 2 = 30 plants. This means we can fit 30 plants on 15L pots in 6m 2 . You can adjust this to any size of growing space just by looking at the table and doing basic math.
Tip : If you really want to fit more plants in your grow space, we recommend using rectangular pots, this will prevent you from wasting space.
5. Calculate Light Potency Based On The Number Of Plants
There are two types of light fixtures: Light bulbs and LEDs.
With LEDs it’s impossible to calculate because the quality of the individual LEDs changes from one manufacturer to another.
The best thing is to follow the recommendations of the manufacturer that should be in the manual of the light fixture, if not, we recommend sending them an email asking for the information
If you tried everything and cannot find the information you need, you can follow the general rule: a 250W LED is equal to a 400W light bulb.
As said before, this is not always true and is only to be followed if you can’t find any other information about the LEDs you’re buying (almost all decent LEDs provide the area coverage and you shouldn’t worry too much about this).
Tip : Even though it’s not recommended because every LED is different if you still want to use this guide for LEDs, you will have to divide the number of watts by 1.6.
So if you were to need 2500W of light bulbs, in LED it would be 2500W ÷ 1.6 = 1562W of LED
Now, with light bulbs this is different and there indeed is a way to calculate the wattage you will need for a number of plants.
Let’s continue with the example we were following before. We рave a growing space area of 6m 2 and we already know we can fit 30 plants in it, what’s the wattage we will need.
Usually, we would need around 75W per plant, so by following the table we can calculate how many watts we would need for 30 plants in a 6m 2 growing space.
|Wattage||Number Of Plants|
|250W||3 big or 4 small|
|1000W||13 big or 14 small|
If you’re growing less than 14 plants, you can just look it up on the table. If you’re growing more like in the previous example, you need to multiply the number of plants by 75W.
So in our example, it would be 30 x 75w = 2250W.
This means we would need 2250W to grow 30 plants on 15L pots in a 6m 2 growing space.
6. How Can Plant Training Help Me In These Situations?
Even though there are a lot of plant training techniques, there are only a few that can be done on autoflowers without any problems.
The Tie-Down Method
With this technique, you will help the branches open up, allowing light to reach deeper resulting in multiple bud sites and denser buds. By doing this, you will be able to fit fewer plants in your grow space but you will get a bigger yield.
Continuing our example, if we had 6m 2 of growing space, we would be able to fit 30 plants. If you applied this method, that would be lowered to around 15 plants, depending on the pot size.
You can follow the table for a general guide:
|Pot Size||Plant Number Per m 2|
In our example, we were using 15L pots so according to the table, we need to multiply the area by the number of plants, so it would be 6 x 2 = 12.
This means we could fit 12 plants in a 6m 2 area when applying the tie-down method. To calculate the wattage needed for those 12 plants, we have to multiply the number of plants by 75W, so 12 x 75W = 900w
Tip : If you need 900W and don’t have the space to have one 400W light bulb + two 250W light bulbs, you can use a 1000W bulb. This will not damage your plants and will only make them grow more vigorously
Obviously, this is approximate and you can fit a little bit more or less, depending on your skills and need.
Sea Of Green (SOG)
When growing in a Sea of Green, the number is higher than in the Tie-Down method and also higher than growing the plant without any kind of training. This is because plant training methods aim to control a plant’s size while also yielding as much as possible.
This method consists of slowly training your plants into an even canopy, allowing light to reach all bud sites equally.
The following is a general guide, and as said before, you can have more or fewer plants depending on your skills and need.
|Pot Size||Plant Number Per m 2|
So, to recapitulate we had an area of 6m 2 where we would fit 30 plants (without training) in 15L pots that would need 2250W of lights.
In our example, we are growing in 15L pots so to calculate how many plants we can fit in a 6m 2 area of SOG, we have to multiply the area size by the number of plants per m 2 in 15L pots, resulting in 6×6 = 36 plants.
Meaning, we can fit 36 plants in a Sea of Green of 6m 2 , and to calculate the wattage, we have to multiply the number of plants by 75W, so 36 x 75w = 2700w
7. In Conclusion
There’s no exact number of plants you can fit in your grow tent, independent of the size. What will truly define that is a combination of your budget, genetics, equipment, and environment.
This guide will help novice growers figure it out, but it’s all a matter of preference.
If you are looking for plants to grow in smaller pots and haven’t decided what to grow in your next cycle yet, we recommend our Zkittlez Auto and Gelato Auto. Both of them grow between 40-100cm and will develop well with LST techniques.
There are several things that help control the size of an autoflower, things like genetics, lights, and pot size make it possible to grow up to 6 plants per 1m2
Autoflowering cannabis plants can sometimes seem magical; they’re still relatively new but they’ve made their own home among enthusiastic growers thanks to their fast harvests and amazing results. When they first came around, people weren’t too convinced of their potential, but things have since changed. Modern autoflowering strains are nothing like the old ones thanks to amazing advances made in genetics and creating hybrids. To be honest, I’ve seen some beauties that I didn’t believe were autos at first.
Like anything though, they have both pros and cons. Let’s start with the cons;
- To ensure they grow big, you’ll need to take special care of them.
- You can’t control how long they veg for.
- You can’t take clones from them.
Of course, then there are the pros;
- They’re extremely fast plants, with as little as 55 days from germination to completion for some strains.
- They can be grown both indoors and outdoors.
- They don’t get stressed out by light contamination nor do they reveg, so there’s no need to worry about street lights interfering with their metabolism.
If you take care of autos properly then you can get amazing, decent sized plants that look nothing like those old autos that used to produce about 2 joints; these plants now produce top quality flavors, aromas and effects, and some would even say that there are strains that are better than simple feminized seasonal plants. You won’t be able to control the growth period, so if you plant them indoors, the first time you plant it should be a test; if you notice a plant growing too tall you can give it less water to stop the growth. If you’re growing in a grow tent, you should plant strains that take two months.
If you’re using a grow room then it doesn’t really matter whether the strain is 2 or 3 months, but make sure you don’t plant too many of them. If you have 2 month strains, 9 to 16 plants per square meter is enough, and if they’re 3 month strains then 4 to 9 is enough. The bad thing about these plants is that you won’t be able to clone any of them even if you wanted to, and growing has to be done through seeds every time.
So, in a couple of months your plants will be ready for harvest, rewarding you with a good yield and quality both indoors and outdoors. Autos are also the perfect way for many people to get around the pesky problem of street lights; they can cause plants on balconies to have issues with flowering due to having their dark cycle cut off, but autos aren’t influenced by light and they’ll flower perfectly under 24h of light; for indoor plants 20h of light is needed to get the most out of them.
There’s a huge amount of auto strains to choose from. There are bigger ones, smaller ones etc. depending on what other strains they’ve been crossed from. The fastest ones tend to come from a Critical or Skunk cross (AutoMass, Sweet Skunk…), whereas the bigger but slower ones tend to come from Jack Herer or Haze (Deimos, Magnum, Big Devil XL…). Now you can forget about waiting 4-5 months for your Haze, and plant a 3 month Magnum that has the exact same potency and taste, getting up to 100g.
Some of the Best Auto Strains:
Sweet Skunk Auto by Sweet Seeds
This strain takes two months indoors, with some long and thick buds right at the top of their branches. It’s extremely resinous and even the biggest leaves end up covered in perfect little trichomes and you can later use them to get amazing hash or BHO extracts. You’ll need to grow them in 7L pots, any bigger is unnecessary. These plants grow nicely, opening out their branches to allow the light to reach everywhere.
Due to how fast it grows, you’re going to need to be careful with how you water it at the beginning or you might end up with a dwarfed plant; I’ve managed to get 50g per plant with 9 plants under a 600w lamp. It has an earthy, sweet taste with a warm effect on your body that can even make you sweat, making for a nice relaxing sensation, especially after a long day at work. It looks ready to harvest around 45 days in, but trust us when we say that you need to wait those full two months if you want the best buds possible.
Deimos by Buddha Seeds:
These seeds take three months indoors even if it says from 60-70 days on the package; let them grow for 70-90 days under 20h of light, and don’t be in any rush to harvest them. These plants are gigantic, creating beautiful long colas of buds; they might not be the fattest buds but they’re extremely hard and compact. There are two phenotypes within this strain, one that begins flowering earlier and another that doesn’t seem like it’s going to flower at all.
The faster ones are ready in 70 days and can give you 80g in 7L pots, although you can plant this beauty in 11L pots if you want to. The slower ones begin flowering around day 40, and they’re the biggest ones with the record being held at 125g in a 7L flowerpot. Here’s a picture of it:
Deimos seeds have a rather long growth, so it’s hard to mess up so badly they end up dwarfed, and you should be able to get a nice 40-50 grams even if you’ve don’t something wrong. These plants like to eat a lot, and mine got to a 2.5 EC and had no issues, when I went to wash the roots out it went yellow from nutritional deficiencies and went entirely yellow by the time I harvested it 15 days later, but I got the most out of its flavor and potency.
It’s both incensed and earthy at the same time, having a hint of Jack Herer in it without a doubt; it’s neither overly relaxing nor too energizing, making it perfect for smoking during the day even when you have things to do.
Big Devil XL by Sweet Seeds:
Personally, this is one of my favorite tastes, with a nice and deep incensed taste that lingers. I planted a few and they were all pretty balanced in grow, same size and same yield ranging from 90g to 100g, although I got 30g from one that I deliberately overwatered at the start to see the difference between overwatered plants and properly watered plants. I have the dwarfed plant the same light and food, just more water, and even then it gave up 30g, making this strain a recommendable reliable auto strain.
The entire cycle takes around 90 days indoors under a 20h light period, and you’ll need to use preventive treatments for fungi as this strain doesn’t seem to have much of a resistance to fungi and you don’t want to risk an oidium infection. If you take care of this strain properly, place it in a nice sunny area and give it some soil that’s rich in nutrients, then all you’ll need to go is give it some bud fattening product towards the end of the second month. If you grow organically, make sure to make a nice mixture of guan in the substrate and use a fertilizer base like Bio Flores by Canna or Bio Bloom by BioBizz. Make sure you don’t harvest too early or you’ll lose quite a lot of yield, as that last month is really when the buds fatten up and get harder.
Here’s a couple of pictures of my indoor Big Devil XL’s, and an example of one that was over watered; if you over water at the start you’ll end up with a plant half the size of the one it could be, and I didn’t even over water this one that might. We got 30g from this plant, but severe overwatering on a 2 month plant will cause you to end up with 4 joints on one plant.
Magnum by Buddha Seeds:
This autoflowering plant is absolutely gigantic, and it’s perfect for growing outdoors in an extremely sunny area where you can get the absolute most out of it. Indoors, this strain can suffer a lot when it comes to heat because you’ll need to move the lights closer to them so it can reach the lower branches properly, and then it grows quite tall and only the tips of the branches develop correctly, so we don’t recommend this for indoor grows. It grows out nice long branches with buds all over. The buds are spongy and not too hard, meaning that it’s resistant to rot. It has an incensed taste and gives great quality buds in as far as weed and resin. They grow really tall, kind of like Christmas trees, and the branches are strong enough to put up with the weight of the buds.
This strain takes three months to completely finish its cycle, from germination to harvesting and you can get over 100g from just one properly taken care of plant. This strain also absorbs quite a lot of nutrients, so you can use quite a large dosage of flowering fertilizers, especially if you don’t want to end up with yellowing leaves all over your plants or a low yield. It’s also pretty hard to end up dwarfing this strain as it begins flowering around 40 days after you plant them and by then it will have grown enough to give a decent yield, making it perfect for beginners.
Now that you have a decent idea about which are the best (personal opinion) auto strains out there, you can get to planting them like any other plant. They’ll give you an amazing yield, an incredible flavor and aroma with which you’ll have plenty of good times with your friends or on your own. Submerge yourself in the world of autoflowering plants and you’ll learn how to get the most out of them. You can do various grows during the year outdoors and indoors, doing up to 6 grows a year in a grow tent. In grow tents you can germinate when your current plants have around 10-15 days to go, harvesting once every 45 days. Get ready to get some amazing yields from some amazing strains!
Author: Javier Chinesta
Translation: Ciara Murphy
Autoflowering cannabis strains; everything you need to know, including a list of our personal favorite autoflowering strains.