How can you increase growth and yield from your grow space?
Do you want to increase your yield of flower and bud? Or maybe you want to boast about your yield per watt to your forum friends. Either way we have 5 ways you can change your growing methods or upgrade your kit to get improved results.
How to Increase Photosynthesis rate for higher growth rates
To increase the growth rate you need to increase the rate of photosynthesis and the related uptake of nutrients.
1. Increase the light intensity for 50% more yield
Most grow lights sold today recommend an average PAR intensity for photoperiod plants of between 800 and 900 µmols/m²/second. This is a good level but recent studies and current practice in the commercial cannabis industry shows that plants will continue to increase growth until about 1,300 µmols/m²/second.
Increasing PAR intensity to this very high level is only recommended for expert growers because all aspects of the grow setup must be dialled in to match including climate control, nutrient delivery etc.
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Photoperiod plants Flowering |
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| Growers level |
PAR intensity (µmols/m²/sec) |
Watts per ft² | Watts per m² |
| High performance | 850 | 40 | 350 |
| Expert performance | 1,300 | 60 | 550 |
The plants have a limited capacity to absorb light over a day. As Autoflowering plants have a longer light cycle, usually about 20 hours, we recommend a lower light intensity.
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Autoflower plants Flowering |
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| Growers level |
PAR intensity (µmols/m²/sec) |
Watts per ft² | Watts per m² |
| High performance | 500 | 22 | 200 |
| Expert performance | 750 | 35 | 300 |
2. Adding a seedling grow light for 33% more Yield
The addition of a small grow area or grow tent to start seedlings and clones is more efficient. It will enable you to improve your productivity and reduce your electricity bills.
Putting a few small plants into your main tent is inefficient. Most of the light is not absorbed by the small plant canopy.
A more efficient setup is to grow your seedlings or clones in small pots under a small grow light. This setup uses a higher percentage of the total light energy. You also use a smaller grow light and therefore less electricity.
Once the young plants are 4 or 5 weeks old you can transfer them to larger pots in the main grow tent.
Reduce your grow cycle time using a seedling light
A lot of growers have one grow tent. The same tent is used to grow plants from young seedlings through the vegetative and flowering cycle to harvest.
The chart below shows you can reduce the time to harvest in your grow room by the use of a main tent (green bar) and a seedling or clone tent (blue bar).
3. Grow more plants in the same space for shorter grow cycles
If you think of the plant canopy like a solar panel the sooner the plant canopy is full and creates a sea of green the better. The plant leaves are like solar panels and will capture more light energy when the canopy is full.
If you have more small plants they will fill the canopy and maximise the potential growth in the tent sooner than few plants that have to grow bigger.
The vegetative time will also be shorter. As soon as the canopy is full you can switch to flowering on the 12 hour cycle.
This does mean more seedlings or clones, more plant pots, more irrigation lines etc. However there is also safety in numbers and you can mix a larger variety of strains in the same grow
4. Upgrade your growing medium to Coco or Hydro for bigger yields
You can increase the growth rate and subsequent yield by up to 50% by using hydro systems. Many people argue that soil grown medicinal herb tastes better but there is not much evidence for this view. However there is an abundance of evidence that soil is the least efficient way to deliver nutrients to your plants.
We have completed two side by side tests with chilli plants demonstrating that coco is more efficient than soil and hydro is more efficient again.
5. Add CO2 to the grow room to increase yields by up to 30%
New research demonstrates that enriching CO2 in your grow room to 1,000 ppm can increase medicinal herb growth by up to 30%.
The best way to elevate CO2 in your grow tent?
Unfortunately it requires some investment in equipment. There are two options:
- Cold CO2 enrichment with CO2 cylinder and valves
- Hot CO2 enrichment with a gas burner
Cold CO2 enrichment
This setup requires investment of about $500 -$1,000 for a CO2 cylinder, regulator valve, controller and sensor. It is more expensive to run than a gas burner but does not produce heat or water vapour when running. It is therefore easier to control the closed environment required to achieve elevated CO2 in the grow room.
Hot CO2 enrichment
Hot CO2 devices burn a pilot flame of gas in a safe container. The system outputs CO2 , water vapour and heat. The CO2 burner costs about $300 to $700 depending on output but you also require a CO2 sensor and controller which cost about $200 to $300. the investment in a hot CO2 burner is more upfront but it is cheaper to run as propane gas is much cheaper than CO2 cylinders.
The additional downside to a hot burner is it generates heat and water vapour which must be removed from the grow room with air conditioning. This is a major additional expense making CO2 enrichment the upgrade which is most expensive and with the lowest return.
