Hi! So, I'm an economist, which means I think about things like money, time, return on investment, etc. a little bit different than most people - that is, formulaic-ly, rather than emotionally (my colleagues might say 'correctly' vs 'incorrectly', but that's kind of arrogant, yes?). Anyhow, I thought I would lay out some of the economics - as in the classical sense - behind starting a new grow. In doing so, I hope I allow people to understand what is the best way they can maximize their investment, and to not get discouraged and to stick with growing.
To start, I think we should dispel a major myth:
the horridly incorrect "rule of thumb" that an efficient grow achieves 1 gram/watt. This is very easy to disprove - say you have 2 methods of growing, method A and method B.
*Method A costs $25/month, and gets you .5g/watt;
*Method B costs $100/month, and gets you 1g/watt.
Which should you choose? Well, assuming you can afford both methods, you should choose method A, and run 4 of them in parallel - this would get you 2g/watt/dollar, as opposed to 1g/watt/dollar using method B. If you know anything about math, you'll also see we can cancel the watts from our units of comparison, and we end up with the factor g/$ spent.
This is a MUCH better metric for growing efficiency than g/watt - and, in fact, when you start looking at grows in the grow journals through the lens of grams/$ spent, as opposed to gram/watt, you start to see why so many people swear by their CFL or LED set-ups. Someone can get 75 grams of weed for $20/month in electric bills over 3 months - so, for the equivalent of $60 in a 3 month grow, you get ~2.5 oz of weed; taking the going (Massachusetts) rate of ~$300/oz of primo herb, that's a final grow valued at $750. In other words, those poor producing, weak CFL grows can give an ROI of 12.5 to 1! Compare that with a typical HID grow, which in the same space and time might result in a harvest of 125 g , but with a cost of almost $40/month to operate - a crop valued at $1300, which gives you an ROI of 11 to 1. The CFL has a better ROI ratio, while carrying less risk; less risk of fire, less risk of exposure to the authorities, etc. That is not to say CFL's are better than HID's, per se - only that there is more involved in the economics of the choice than g/watt.
So, we've established that a better metric of the returns on growing are grams/dollar. How do we calculate what is the most effective rate of return for our material? I'll use my grow-set up as an example:
* Mars II LED Grow Light 1200W, $450.
* Grow Tent 3' 3'' x3' 3'' x6'', $100
* 6 inch In-Line Fan 400 CFM, $80
* Carbon Filter, $75
* Fan speed adjuster, $20
* Growology nutes, $60
* 2 black widow grow buckets, $100
* ph kit, ph meter, tds meter, comes in a bundle, $50
* 10 lbs hydroton, $10
* rapid rooters, $10
Total cost: ~$1,000
This gives a grow tent with 3' x3' x6', in a DWC/SCROG grow under a large LED light with a real-world draw of ~535 watts. Going seed to smoke, two plants in this set-up will generate anywhere from 6 - 16 oz for me, depending on time of year, how much attention I'm paying, luck, strain, whether I'm trying anything new, etc. Let's take somewhere in the middle and say 11oz per grow is my average. (Note: the point isn't that my setup is the most economically efficient - I overpaid for the black widow buckets, for example, out of pure laziness - the point is just to get items and prices we can use in a formula).
So, the start-up cost of my grow is $1000. From seed to smoke takes me about 16 weeks; about 6 weeks germination/veg, and about 10 weeks flower (I should really put together a grow journal sometimes soon). I smoke, on average, about an oz/month. So, assuming 16 weeks = 4 months, then while I'm growing, I am "spending" 300/month smoking weed that either (A) I bought, at $300/oz, or (B) weed I grew that I could be selling at $300/oz, were I a dealer. So whether we're talking actual cost, or opportunity cost, the cost of my grow increases by $300/month in weed cost - over the course of a 4 month grow, we are now at $2,200.
But there's electricity, too! My LED draws at 535 watts - my electricity cost, here in Taxachusetts, is $.15/kwh. So, during veg, running at 18 hours a day, I spend about $45/month on electricity for that massive Mars LED (15 cents and hour times 18 hours a day * 31 days per month, divided by 1000 because I'm billed in killowats, and not watts). In flower, using the same formula, I pay about $30. So, in electricity, I pay about $135 over the course of a 4 month seed to smoke grow (it's less expensive when I use clones, but for most people starting up, their first grow will be with seeds, so I'm using that for this example).
So, all in, our first grow has a total outlay of about $2300. To get a positive ROI in our first grow, we need to grow about 8oz weed - (8oz * $300/oz = $2,400); anything less than that, and we're better off buying weed, rather than smoking it! So, how likely is it we can do that?
Well, where that aforementioned awful rule of thumb of 1g/watt comes from, is that on average, 100 watts/square foot of space will net 1g/watt of weed. No, a 150 watt HPS in a 1x1 tent would not net the average grower 150 grams; there is a point of diminishing returns at both the lower and upper bounds. But in general, this rule holds. So, to figure out the average returns of my set-up (and once again, here's where I prove my set-up is sub-optimal in some ways): take light, which is 535watts, and divide it by my 3 x 3 tent, which is 9 square feet, multiplied by the 100 watt/ft^2 ideal: 535/900. You get .594 grams/watt (much less than 1). Now, take that .594 gra,s/watt, and multiply it by my lights true wall pull of 535 watts, and you get 318 grams, or a little over 11 ounces. So the average grower, using my setup, will probably pull in slightly over 11 oz; a stud might pull a pound and a half (and in fact, if you look on YouTube, some people do even better than that). Sometimes I do extra shitty and only get 6 ounces. But on average, I can expect 11 and change. Since I needed to surpass 8 ounces on my first grow to get a positive ROI, I can conclude that this setup is likely to succeed, if success is measured in positive ROI within 1 grow.
NOW - let's look at another option: the British Columbia Northern Lights BloomBox. The BloomBox runs $6500 new; when you include taxes and shipping, you're looking at $7,200. I have a friend who runs the bloombox, so I already know it costs just about the same amount to run the BB as it takes to run my grow (BB comes with 400 watt HID and a CFL germie/veg areas). So, your initial outlay for a similar seed-to-smoke BB grow would be $7,200 capital investment + $1,200 weed opportunity cost + $135 electricity over 4 months. Total cost: $8,535. To get a positive ROI at $300/oz, you would need to grow 28.5 oz of weed, or more than 1 3/4 pounds. That sounds awfully tough 0- is it doable? Well, according to the BCNL website, the flower area of 36" width, 28" depth, for a total area of 7 square feet. Using our formula to determine avg grow potential, we take the 400 watt HPS, and divide it by 700 (7 sq ft * 100 watt/sq ft), and we get .57g/watt avg potential. Now multiply that by the 400 watt HPS you have in the box, and you get...228 grams, or a smidge over 8 ounces. We need 28.5 ounces to reach ROI, which means we would need 5 average size grows grows to reach ROI in the BloomBox! Except...each 16 week grow still adds $1335 in expense - the cost of electricity, and the opportunity cost of the weed you smoke, at $300/oz. When you do the math, you realize it takes an astounding SEVEN 16 week grows to reach positive ROI with the BloomBox! 7 * 16 weeks = 112 weeks, or over 2 years!!!
So, in conclusion - do you know why the professionals don't buy BloomBoxes? because they are HORRIBLE deals. You're far better off buying the components I've listed above (or equivalents), paying someone handy you can trust $500 to put it all together for you, and running with that. Pre-built boxes are a SCAM, targeted at new growers who don't know any better.
I hope you've found this helpful - grow big, and grow profitably (whatever "profitably" means to you)! Thanks for reading!