The 3 limiting factors to plant growth in order: light, CO2, and then minerals in the medium. I wouldn't bother getting a light over 300 watts unless you are going to supply a very large amount of CO2 (I will describe how you can organically later based on research). Adding more light isn't useful unless you are going to add CO2. This post is to suggest that if you are a new grower you should use a 300 watt light. Based on my calculations, a 300 watt vipar spectar which I used for my last grow will max out your plants 1st limiting factor to growth, light, and actually more so. And they are way cheap. What this means though is that my plants required approximately 700 ppm of CO2 or so before running into their 3rd limiting factor of growth, soil minerals. With the greenhouse effect, we have around 430 ppm CO2 in the atmosphere. Therefore, there is no point in getting a stronger light than 300 watts. As a matter of fact, you won't even reach the full potential of the 300 watt light until you supplement some CO2. A 600 watt light is not necessary until you will be delivering at least around 800 ppm of CO2 or so, compared to a 300 watt light. And at 600 watts you'll be wanting over 1,000 ppm CO2. TLDR; I maxed out my plants 1st limiting factor w/ a 300 watt light and then supplemented CO2 by having the grow tent cycle on while I would be sleeping in there. I also kept a window open so my CO2 wouldn't rise too high. CO2 can get absurdly high in bedrooms sealed overnight with people sleeping in them though. How to add large amounts of CO2 and unlock the 2nd limiting factor to plant growth, organically:
1. hang out around your plants. You breathe out a lot of CO2, about 22,000 ppm. Get it to your plants anyway you can. Bedrooms CO2 ppm can actually rise to 2,000 just from sleeping overnight if you have a roommate and keep the room sealed. Have your grow space near a place where you hang out!
2. A mushroom grow room. Mushrooms supply a lot of CO2 as they grow and reproduce. If you grow mushrooms off of a mushroom patch, you should definitely have it by your grow room. Better yet, grow mushrooms beneath your cannabis! An oyster mushroom patch for instance, can produce 280,000 ppm CO2 over its lifetime.
3. Make sure your environment suits your plants' transpiration needs. A plant can't transpire (absorb CO2) unless the rH is 35-70%. Temperature is also important. Make sure to grow plants in the right environment so they can benefit from extra CO2. 4. Don't! Add a synthetic CO2 system to boost your yields.
Check out the flower I grew w/ a 300w light, some CO2 from sleeping around em (night time light cycle) and good compost and compost teas...
Purple Punch. I like to leave the trim on like Chef B lol. Yield wasn't the best because of poor pruning but I still got a few ounces, based on there being a few quart mason jars full in the end. I would have changed a few things about this grow, but these are the best flowers I grew. The high is like a hammock of the mind. Please comment if can think of other creative ways to add CO2. CO2 is usually the best way to rapidly increase yields, not increasing light. Again a 300 watt light will likely max out your CO2 needs. You can organically peak a 300 watt lights CO2 needs but you would need to hang out with your plants a lot or grow a lot of mushrooms to get a consistent growth boost. A 300 watt light is most realistic unless you are maybe in a completely sealed house because your CO2 probably won't reach higher than 700 ppm. I guess in winter grows where people have sealed homes would benefit from a better light (like a 600w) as the CO2 might reach over 700 ppm, and many people garden indoors during the winter. This would also improve air quality in the home, compared to a 300w light. However, I think 600w lights are a little more sus on the e-bill just to say