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What Determines Your Yields? (aka "The Limiting Factor")
by Sirius Fourside
One of the most common questions we get asked by new cannabis growers is “How much bud can I expect to yield with my setup?”
It’s a tough question to answer accurately since there are so many variables that affect your yields, the grower being the biggest one of them.
But it’s a valid question! People can be - understandably - timid about starting to grow cannabis, and they want to make sure they know what yields to expect. No one wants put in money and effort into something if they feel they won’t be happy with the results. That’s where the yield ‘limiting factor’ comes in.
In nature, a limiting factor is something that is key in restricting the size of a population. For example, the number of healthy foxes in an area plays a very important role in how many rabbits can live in the same area. Foxes are a limiting factor to rabbit populations; foxes are a factor that limits the maximum population of rabbits in their area.
What cannabis yields can you expect to harvest from a specific grow light or setup?
When growing cannabis, a limiting factor is something that is integral in determining how much bud you can harvest. For example, if you grow a high-yielding strain under a 1000W light in a solo cup, the solo cup becomes the limiting factor in that it’s the main factor that’s limiting how much the grower can harvest.
It would be tough to guess exactly how much you’re going to harvest even with detailed information about a grower’s entire setup because experience makes a huge difference. However, by identifying the limiting factor in a cannabis growing setup, we can get a good approximation of what a grower can expect for yields (providing everything goes normally).
How This Works
In the next section we’ll go through five aspects of a grow setup that have a major impact on your yields: grow space, grow lights, container, strain and plant training. Although all five of these aspects affect your yields, we only use the grow space, lights and container to give you an expected weight range for yields. We’ll explain that part a little later.
Generally, a grower should expect to harvest an amount of bud close to the lowest expected range from grow space, lights or container. Unlike your setup where yields can be more predictable, breeder-specified yields aren’t that reliable, so although some strains yield better than others, the strain you choose is more of a preference. Plant training is another factor that can increase your yields indoors, but after the other factors are calculated.
There are two very important things to keep in mind about this info:
- Each grower’s unique set of skills can drastically change the amount of bud harvested from a grow. This guide is meant to give you an idea of what ballpark figures to expect; they’re not set in stone!
- Every item in each of the topics we discuss will have a range, for example: 1oz - 10oz. The low end of that range (1oz) assumes the grow didn’t go so well and that you’re using equipment in the lower end of the range you’re in. Conversely, the high end of the range (10oz) assumes the grow went great and you’re using equipment in the upper end of your range! So in the 1oz - 10oz example:
- 1oz would be close to what a grower should expect to harvest if the plant was unhealthy and grown with weaker equipment.
- 10oz would be close to what a grower should expect to harvest if the plant was healthy and the grower used better equipment.
Your ‘Grow Space’ is the area your plants call home. This could be a grow tent, a cabinet, a closet, a PC case, a room in your house or the great outdoors! Basically, it’s the area that physically limits how big your plants can grow (with walls, fences, etc.).
- Expected yields: Up to 1oz
Small Tents & Larger Cabinets - up to 9ft² (0.84m²)
- Larger than a PC case, but not larger than a 2‘x4’or 3’x3’ area (not larger than 0.7m x 1.2m or 0.9m x 0.9m)
- Taller than 3.5 feet (1 meter)
- Expected yields: 1oz to 10oz
Hobby Level - 10ft² - 25ft² (1m² to 2.5m²)
- Larger than 3’x3’, but no larger than a 5’x5’ space (from 0.9m x 0.9m to 1.6m x 1.6m)
- Taller than 6 feet (1.9 meters)
- Expected yields: 7oz to 2lbs
Large Tents/Rooms/Etc - 26+ft² (2.5+m²)
- Larger than a 5’x5’ tent (larger than 1.6m x 1.6m)
- Taller than 6 feet (1.9 meters)
- Now we’re nearing the ‘grow op’ size, so the yields can vary by a wide margin as the tents turn into rooms
- Expected yields: 2lbs+
- Outdoor yields vary wildly depending on the grower and the amount of growing space available. The amount of direct sunlight a plant gets each day also plays a huge factor!
- Expected yields: A few ounces to many pounds
Your lights are the the energy generator that powers all of your plant’s actions. Your grow bulbs produce light, your plants turn that light into energy, and that energy fuels the growth of leaves, stems and buds. Generally, more light grows larger plants!
- These are the old-fashioned house lights that were replaced with CFLs and LEDs.
- NEVER USE THESE TO GROW CANNABIS!
- Expected yields: : ( (yes, that’s a sad face)
Stealth lighting (<100W)
- Usually consists of 1-4 CFLs, 1-2 LEDs, or a T5 array
- Expected yields: A few grams to 50g
Smaller lighting (101W - 300W)
- Usually consists of a bunch of CFLs or a few high powered ones, 1-3 LEDs, a T5 array, or a single small HPS
- Expected yields: 15g to 9oz
Medium lighting (301W - 600W)
- At this point, the majority of all indoor lighting is either LEDs or HPS
- Expected yields: 5oz to 20oz
High-powered lighting (701W - 1000W+)
- Can be LEDs, but is generally HPS lighting, especially over 1000W. Commercial growers use multiple 600 or 1000W HPS lights which means the potential yields can vary greatly.
- Expected yields: 10oz to 2lbs+
Bonus Information: Ok, now that you have some examples to give you an idea, here’s the general formula we use to determine what yields can be expected for each type of grow light. This is not exact in any way, but is a good place to start if you’re looking for a ballpark figure.
CFLs, T5s and Other Fluorescent Lighting: 0.25g/watt
HPS and LEDs: 0.5g+/watt
When talking about “watts” I mean the amount of watts being pulled out of the wall by the light, so no “equivalent” numbers. You’re interested in actual power draw.
And just like a hard hat (or a hat of any type, really), it’s very uncomfortable to wear one if it’s too small. Similarly, cannabis plants don’t like spaces that are too small for their root requirements. Limiting the size of a plant’s container has a direct effect on the maximum size of the plant, and thus, its maximum yields.
Note: DWC containers are counted in this group as they seem to make for faster growth, not necessarily more bud harvested.
- Solo cups are great for stealth or people that are timid to start purchasing equipment to grow. Expect these to be tiny!
- Expected yields: up to 1 oz
Very Small pots (1-2 gallons)
- Often used for a Sea of Green (SoG) training scenario, or as an in-between container during the transplanting process. This can also be a good pot size for someone trying to limit their plant's growth via purposely making them rootbound.
- Expected yields: up to 4 oz
Small pots (3-5 gallons)
- For mid-size grows, and smaller grow tents.
- Expected yields: up to 10 oz
Medium/Large pots (6+ gallons)
- This group consists of pots that are more than 6 gallons in size, or plants that are planted in the ground with plenty of root-room.
- Expected yields: up to many pounds
Over the years, cannabis cultivation has become a lucrative niche for some in addition to being a fascinating hobby. This has lead to there being a large availability of high-potency, well-tested and high-yielding strains that available to growers all over the world.
We’ve taken a bunch of breeder-specified yield amounts and averaged them to get this range. However, you should always take breeder specified yield amounts with a HUGE grain of salt as they tend to overestimate the capabilities of their products...imagine that! In the interest of making sure this guide stays straight-forward, we won’t count the strain towards the limit if only because the information is so unreliable. We’ll give you our version of what to expect and let you make the choice!
Important: We believe your personal preferences should always take precedence over possibly high yields. Some strains are bred to be high-yielders, some are bred to be potent and some are bred to look, smell and taste great.
Some strains are bred to have it all, but most strains are bred to just be excellent at one thing. Before you ever dismiss a strain due to its yields, be certain to research its effects first so you don’t pass on something great! Plus, you might pass up a good strain for a high yielder than doesn’t actually have high yields!
- Autos that finish fast and small, and ‘boutique’ strains can belong to this group
- Expected yields: 0.5 oz/plant to 3.5oz/plant
- Translation: You can expect lower amounts than ‘normal’ with these strains. Some autos can grow 15g, but other autos can yield multiple ounces. If we could make yields into simple numbers, we’d consider this group to produce 80% (0.8) compared to average yielding strains based on the median yield.
- Many photoperiod and some ‘super-autos’ fall into this category
- Expected yields: 1 to 7 oz per plant
- Translation: Consider this the baseline for a ‘normal’ yielding plant. In our book, medium strains are what we’d consider 100%, so we give these a strain factor of 1.0 based on the median yield. You can grow any photoperiod plant as big as you like so you could definitely yield more, but we’re talking about an average plant.
- High yields equates to more sales for breeders, so you can expect this category to grow faster than the other two. Most strains nowadays fall into this category...or at least claim to! Remember to research and stick with good breeders!
- Expected yields: 2 to 8+ oz per plant
- Translation: These strains were bred to produce lots of bud, so they typically yield from a bit more to a lot more than ‘normal’. If we could make yields into simple numbers, we’d consider this group to produce 120% (1.2) based on the median yield.
Training is like putting your plants on an exercise regimen! You train the plant into a shape that squeezes bigger yields out of your indoor grow lights, and also allows you to produce bigger yields in a smaller space. You might not be able to turn a naturally low yielding plant into a 2lb plant, but you can definitely make that little guy tougher and more productive than it used to be!
Unlike the other sections, training doesn’t limit your grow to a certain amount. Rather, it builds on the traits identified in the other sections; it’s like a bonus!
- 100%; Not training your plants means there will be no positive or negative effect on yields
Light training (light LST, single top/fim)
- Light training can make for much better use of your indoor grow lights. You essentially are getting more out of the same amount of resources.
- Up to 150%
Heavy training (ScrOG, Mainlining/Manifolding, defoliation, etc.)
- Heavy training can offer the largest return on your investment, but it also tends to be the most dangerous for plants. Some heavy-training methods can drastically reduce yields or even kill plants when done incorrectly. However, these same methods in the right hands can dramatically increase the amount of bud harvested.
- -100% to 200%. In other words, ranges from dead plants to harvesting twice as much bud. It’s a gamble for beginners but becomes extra free bud with a little experience!
Using This Information
Alright, so let’s see this information applied to a few hypothetical cases! All we’re doing is finding which respective group their equipment belongs in and finding which one is the limiting factor by locating the lowest maximum. The result is a good estimate of what a grower could expect to harvest in a ‘bad to average’ range. Remember, we’re only factoring in grow space, lights and container.
Find the Limiting Factor (lowest number)
- Grow Space
- Grow Lights
Jim is growing cannabis in a 3-gallon pot in a 4’x4’ tent with a 216W T5 light
- 4’x4’ tent range group range: 7oz to 2lbs
- 216W light group range: 15g to 9oz
- Side Note: This light is a T5 (which gets an average of 0.25g/watt) and pulls 216W out of the wall, you can use the equation 216 x 0.25 = 54 grams or 1.9oz
- 3-gallon container group range: Up to 10 oz
In this case, Jim’s lights have the lowest maximum and are therefore the limiting factor. Jim can expect to grow about 1.9oz in good conditions, or more with successful training. But in order to get significantly higher yields to match the other limiting factors in his tent, Jim would need to update his grow light setup.
Robert has some plants growing in solo cups in a PC case with 150W of CFLs
- PC case (stealth) group range: Up to 1oz
- 150W light group range: 15g to 9oz
- Side Note: These grow lights are CFLs (which get an average of 0.25g/watt) and they pull a total of 150W out of the wall, you use the equation 150 x 0.25 = 37.5 grams or 1.3oz
- Solo cup group range: Up to 1oz
Robert’s small container and case slightly limit his maximum yields, but this is overall a good match! Robert can expect to grow as much as 1oz in good conditions.
Kayla is growing plants in a 11’x9’ room, in a 8-gallon DWC container with a 300W LED (pulls 300W out the wall, which is it’s ‘actual power draw’ and not based on number of LEDs or equivalency numbers)
- 9’x9’ grow area group range: 2lbs+
- 300W light group range: 15g to 9oz
- Side Note: Because an LED gets an average of 0.5g+/watt, and this particular model pulls 300W out of the wall, you use the equation 300 x 0.5 = 150 grams or 5.2oz
- 8-gallon container group range: up to many pounds
Kayla has the space and container for a massive grow, but her lights will hold her back. She can expect as much as 9oz in good conditions, but bigger lights could yield her much more!
Stephen has his plants in a 3 gallon container in a 2’x5’ tent under a 100W incandescent bulb.
- An incandescent bulb?! Bad, Stephen! You read this article again and think about what you’ve done!
Hopefully this guide should give some growers a little more insight on where yields actually come from. Again, strains DO have a major impact on your yields, but until we as a community have more reliable information that as a factor, it's best to go with strains you like and judge their performance yourself. Also, don’t forget that good training is like a potential bonus that can increase your yields in addition to our estimations!
Finally, remember that this article is just a bunch of general guidelines. We've seen growers with numbers that totally break our efforts at categorization and we wouldn't have it any other way. In fact, we challenge any growers reading this to smash our numbers are force us to rethink averages! Good luck and enjoy your harvest!