The Grow Mentor (TGM) is me; just a regular citizen who has a family a career and all the trappings of an average middle-class citizen living in the good old US of A. I'm also an avid marijuana cultivation and preparation enthusiast in my spare time. I'm not a professional horticulturist, nor am I an authority on plant biology or any related sciences. However, I've been successfully growing marijuana indoors since it became legal for medical use (about 10 years ago) where I live. It has since become legal for recreational use in my region as well.
My very first -and perhaps the single most important- piece of advice to the aspiring weed farmer is to acquire and read a copy of Ed Rosenthal's excellent "Marijuana Grower's Handbook."
If you are truly interested in growing marijuana and doing it correctly from seed to harvest, then you should invest the time and money and get a copy of this invaluable guide on all things marijuana. Ed Rosenthal is the authority on the science of cannabis cultivation. And the great thing about his book is that while it is certainly filled with plenty of technical, scientific information and terminology, the book is not overly technical. Most of the information is presented in layperson's terms and very easy to follow and understand.
Acquiring and reading this book was the first piece of advice about growing weed that I was ever given and it really paid off for me because there were literally dozens of aspects to setting up a quality indoor marijuana garden that never even occurred to me. I didn't think much of the advice at the time and went ahead and attempted to grow a marijuana plant in my backyard. I will spare you the details but 3 months later -and long before the plant reached maturity- I chopped it down and "hung it upside-down" because that's what I had "heard" you're supposed to do. Where had I "heard" that? Who knows? What I can tell you today is I learned all about how to grow cannabis to maturity and how to properly harvest and cure it from Ed Rosenthal's book. Before reading that book I was ignorant to many of the key characteristics of the cannabis plant. After reading the book I made a conscious vow to myself that if I was going to grow marijuana indoors I wanted to do it the right way. So I followed the guidance in Mr. Rosenthal's book and I have been successfully growing indoors ever since.
Now, please understand that I have nothing to gain by suggesting this book, other than hopefully working towards achieving the ultimate goal of this web site, which is to help people who are 
new to growing marijuana avoid making all the same costly and time-consuming mistakes I made when I was first starting out. If you want a copy of Mr. Rosenthal's book, here's a link to it on Amazon.com (link opens in a new window). Again, I am in no way affiliated with Mr. Rosenthal or his publisher, I just adamantly believe in the value of science and data and the harvests I've had in the last few years suggest that science and data are the best path forward for anyone interested in succeeding with marijuana cultivation. There is plenty to learn, but the good news is you can begin putting your plan in motion immediately by following our "Indoor Marijuana Garden Startup Guide."
Back In The Day
In the beginning -the year 2012 when marijuana was legalized for medical use where I live- I purchased a "SuperStar Smart Grow Box" by a company called Super Closet. In hindsight, this was a colossal waste of money! But at the time I still needed to be as stealthy as possible with my growing since not everyone in our life back then would have accepted it. And unfortunately, to this day, despite widespread legalization for recreational use, marijuana users are still stigmatized in some corners of society. So, it was with an eye towards avoiding this stigma that I purchased the Super Closet.
There are many different shapes and sizes of these kinds of grow enclosures. The version I purchased is 5' tall and 2' x 2' wide with an upper chamber for growing seedlings and a lower chamber for growing and flowering marijuana plants. At the time, I knew very little about how to grow marijuana and so having read about hydroponics on the internet I had learned that growing marijuana hydroponically results in a shorter grow cycle meaning that a dedicated and disciplined gardener could potentially manage to produce up to 4 harvests per year (once every three months). Which is very fast!
This was said to be faster than gowning in dirt and since I'm very much a science geek, the idea of mixing nutrients into the water for something called a "Deep Water Culture" hydroponic grow system was intriguing and in practically no time at all, I had the Super Closet cabinet delivered to my home, along with all of the accessories necessary to grow marijuana in a deep water culture hydroponic configuration.
To make a long story short, I had a moderate level of success on my very first hydroponic grow, yielding well over 1/4 pound of quality flowers (i.e. "buds") of a variety of strains that I'd purchased from an overseas seed source known as "Herbies Seeds." That was over 10 years ago and while Herbies is still in business selling seeds, these days you will need a credit card capable of "international transactions" if you want to buy seeds from most overseas distributors. Most standard Visa/MasterCard/Discover credit cards do NOT have this feature enabled by default. But you can easily get it turned on by calling your credit card company and requesting an international card.
I continued growing in the Super Closet 2' x 2' cabinet and despite having only 200 watts of LED power in the cabinet's lighting system, I managed to bring my average yields up into the neighborhood of 1/2 a pound per harvest, but it was becoming apparent that if I wanted to increase my yields (which, of course I did!) it would be necessary to increase the size of the growing area as well as the intensity and output of the lighting system. It was at this point that I purchased a 3' x 3' Gorilla Grow Tent and a brand new 600w BloomBossTM Fusion-600 LED grow light with "vegetative" and "flowering" growth settings to optimize output based on the grow cycle.
The difference in the plants and how they grew in dirt as compared to water was substantial and obvious from the very first grow in the 3' x 3' tent. But growing in a larger area with hydroponics was becoming more and more challenging because for a hydroponics system to function properly it requires nearly constant maintenance and tweaking to ensure that it's functioning as expected. There are multiple potential points of failure in a hydroponic grow system, depending on the type of system one is using. Deep Water Culture (DWC) requires pumps that have moving parts that don't last forever. A common DWC architecture is every reservoir gets 2 submerged water pumps and 1 submerged set of air stones or some other physical device that releases air into the water to help oxygenate it. Every one of these little pumps is an eventual failure point.
For example, in a Deep Water Culture (DWC) hydroponics system, the roots of the plant are in a reservoir filled with a solution of water mixed with nutrients. That water must be monitored and maintained so that the level does not sink too much to expose your plant's roots to the air, which is not a good thing in a DWC system where the roots must always be fully submerged in the solution.
Another consideration with DWC is the fact that your reservoirs need to be drained completely then immediately refilled with fresh nutrient solution. This must happen once every 5 to 7 days thoughout the entire grow cycle.
Another aspect of growing in a DWC hydro configuration is that if you put multiple plants in the same reservoir all it takes is one small mistake when preparing your liquid solution for the reservoirs and every plant in the reservoir in which you made the mistake suffers the same fate because they're all sharing the same root space and food source (i.e. the "water" in the DWC reservoir).
Because there is no "watering" in a hydroponics system, many make the mistaken assumption that it's less work. I'm here to tell you that the opposite is true. Hydroponics systems are great if you have the time and skill to maintain them, but I found that maintaining a 3' x 3' grow tent with a DWC hydroponics setup to be far too time-consuming for it to fit into my lifestyle, which includes a full-time day job.
But overall, just generally speaking, I found managing the DWC hydro system to be tedious and very time consuming, especially after my best friend, who is also a marijuana grower, convinced me that growing in soil is easier (meaning less work) than hydro, just not as fast. Turns out, he was 100% correct. It's much less time-consuming to manage a soil-based garden - I don't see myself ever going back to hydroponics. There is absolutely nothing wrong with hydro at all, it just didn't work with my lifestyle; I couldn't find enough time to keep it running the way it should have been.
Contrast that with my most recent 3 harvests, which occurred over a period of about 12 months, produced 52 ounces of top-quality flowers. (i.e. "buds") and another 6 ounces of "popcorn buds" or immature growth from the lower parts of the canopy - these are great for making canna-butter, which is used to make pot cookies, brownies, fudge, etc. How did I manage that? By upgrading from a 600-watt LED in a 3' x 3' tent to a 750-watt LED in a 4' x 4' tent, that's how! I got sick of watching my best friend raking in 20+ ounces almost every grow in his 4' x 4' tent with his 1000-watt HPS. I am now producing more than my best friend is producing and I'm doing it with an LED light which runs at about 50% of the cost of his 1000-watt HPS. It adds up when you have an electric bill that's north of $500 every month because you're growing marijuana indoors. That's growing with incandescent lights which are very expensive to run.Traditionally, Metal Halide incandescent lights have been used for the vegetative growth stage, then HPS for flowering because the light from an HPS leans into certain wavelengths that flowering plants crave.